The e-up!

The Volkswagen e-up! Click to enlarge.

One of the hallmarks of the e-up! is its efficiency, with energy consumption of just 11.7 kWh/100 km. At an average electricity price of €0.258 (Germany, July 2013), driving 100 kilometers costs just €3.02 (US$4.00). The efficiency of the e-up! is attributable to the very good cD value for a car of this size of 0.308 (4% lower than its cousin the take up!); optimized rolling resistance (7% lower); the generally energy-saving drive system components; the effective regenerative braking system; innovative equipment modules; and a newly developed, particularly efficient air-conditioning system.

Drive system technology. A compact electric motor (60 kW / 82 PS and 210 Nm starting torque), the lithium-ion battery integrated into the floor and the power electronics form the hub of the new high-tech car’s drive system. The electric motor’s power is transferred to the front wheels via a single-speed gearbox.

Motor and gearbox assembly. Click to enlarge.

Volkswagen itself developed all of the components, including the battery. With a top speed of 130 km/h (81 mph), the average range of the e-up!, dependent on route profile, driving style and payload, is between 120 and 160 km (75 to 99 miles); at very low outdoor temperatures the range may be less. These range distances work especially well in urban areas and for the majority of commuters, Volkswagen notes.

In Germany, for example, studies by the Federal Ministry for Transport, Building and Urban Development found that around 80% of all car drivers in Germany—from job commuters to drivers who make frequent journeys—drive less than 50 km (31 miles) daily.

The e-up accelerates from 0 to 60 km/h in 4.9 seconds; within 12.4 seconds it reaches 100 km/h (62 mph). In 10.5 seconds it accelerates from 80 to 120 km/h. Top speed is 130 km/h (81 mph). By way of comparison: the most powerful conventional e-up! (with 55 kW / 75 PS) accelerates from 0 to 100 km/h in 13.2 seconds and from 80 to 120 km/h in fourth gear in 15.5 seconds.

Battery pack. Click to enlarge.

Li-ion battery. The lithium-ion battery fitted in the e-up! into the vehicle floor weighs 230 kg (507 lbs) and comprises 17 modules, each with 12 cells. These 204 cells add up to a rated voltage of 374 V and rated power of 18.7 kWh. At peak level the cells provide an effective power output of 75 kW and over a continual period 35 kW.

The cell modules of the battery, measuring 1,726 mm long, 1,132 mm wide and 303 mm at its highest point, have been integrated in a space-saving fashion within the floor of the e-up!. Compared to other lithium-ion cells (e.g. from the field of consumer electronics), the battery system’s cells are particularly resistant to heat and cold; no separate battery cooling or heating is required. Like the electric motor and the gearbox, the battery system, battery electronics and the relevant control software were also developed in-house at Volkswagen.

Power electronics. This module weighs 10.5 kg (23 lbs) in the e-up! and, acting as the link, controls the flow of high-voltage power between the e-motor and the lithium-ion battery (depending on battery voltage between 296 and up to 418 V). In doing so the power electronics convert the direct current (DC) stored in the battery into alternating current (AC) and use this to drive the motor. Via a DC/DC converter it also supplies the vehicle’s circuitry with voltage of 12 V.

The power electronics module is connected to the e-motor via the sort of yellow-and-orange 3-phase cable typical for electric vehicles. The connection to the lithium-ion battery is established via two traction cables.

With respect to the power electronics, a distinction has to be made between two fundamentally different modes in which the e-motor operates: motor mode (propulsion) and generator mode (regenerative braking). In motor mode the power electronics use high-power transistors to convert the direct current (DC) stored in the battery into 3-phase alternating current (AC). In generator mode, meanwhile, the alternating current is rectified for charging the battery. In this scenario the power electronics resemble in terms of their task a valve that lets the electrical current flow only towards the battery to be charged. This maximum phase current of the power electronics is limited in the e-up! to 385 A.

The 2.5-kW DC/DC converter integrated into the power electronics is responsible for supplying the vehicle’s 12-V power circuit and thus works like a transformer. The 12-V power circuit and the high-voltage circuit are completely separate from each other in the vehicle. Also included in the power electronics are the controller for running the management software and a CAN interface for communication with control devices.

The power electronics module also dampens the effects of any sudden loading of the drive system (for instance, at moments of sudden acceleration) by regulating the torque accordingly.

Electromechanical brake servo. Electric cars are essentially equipped with two brake systems independent of each other: a conventional, mechanical, hydraulically operated brake system and the e-motor acting as a motor brake when when recovering energy. These two types of braking now blend together in the e-up! with the electromechanical brake servo.

Regardless of regeneration mode (‘D1’, ‘D2’, ‘D3’ or ‘B’), when operating as a generator the electric motor generates a degree of braking torque on the wheels—dependent on its speed and the battery’s temperature and charge level. The variable parameters—motor speed and battery state—lead to fluctuating levels of electric braking. These fluctuations need to be hydraulically compensated and the degree of deceleration matched in this way to the braking performance called for by the driver. The management of the brake system required for this is called brake blending and is achieved via the new electromechanical brake servo. Volkswagen has succeeded here in its primary aim of making maximum utilization of the e-motor’s potential to slow down the e-up! in order to increase its range.

As the majority of braking processes involve only minor or moderate deceleration and are therefore executed without any wear via the e- motor, the electric system helps to keep the conventional brakes in top condition longer.

Range. The e-up! is able to switch off temporarily unneeded consumers and in general to transform kinetic energy produced when coasting or by braking into electrical energy and to store it in the battery for boosting the range of the vehicle.

The range of the e-up! can be varied via three different driving style profiles: the standard mode (automatically on); ‘Eco’; and ‘Eco+’.

• Anyone traveling short distances will stay in standard mode.

• For drivers wanting to extend the range, the first option is the ‘Eco’ mode. The effects of selecting this mode include paring back the e-vehicle’s maximum power output to 50 kW and limiting its top speed to 115 km/h (71 mph). In parallel with that the electronics reduce the output of the air-conditioning system and modify the response curve of the accelerator pedal.

• In ‘Eco+’ mode the electronics limit maximum power output to 40 kW, modify the performance response curve and disable the air conditioning; in this mode the car can reach a top speed of 90 km/h (60 mph).

Over and above the driving style modes the range of the e-up! can be influenced via the regenerative braking function, of which there are five levels available: ‘D’ (regeneration via electromechanical brake servo only when applying the brake), ‘D1’, D2’, ‘D3’ and ‘B’.

In an electric car this number of levels leads to a different way of driving. By means of regenerative braking drivers can appreciably slow down the e-up! by lifting their foot off the accelerator. Used in an anticipatory way, regenerative braking thus replaces use of the brake pedal in many situations. At levels ‘D2’, ‘D3’ and ‘B’, the deceleration via regenerative braking is so strong that in this case the brake lights automatically come on. If the battery is fully charged, no regenerative braking occurs.

• D. The e-up! starts by default in the ‘D’ setting. In this setting there is deceleration kinetically induced through rolling resistance as soon as the driver’s foot is taken off the accelerator (‘coasting’), but no recovery of brake energy takes place. Whenever the driver ‘steps off the power’, though, or when the e-up! is going downhill it rolls perfectly. And that too reduces consumption. When the e-up! is slowed down fairly sharply via the hydraulic brake system it does, however, recover brake energy even in the ‘D’ setting.

• D1, D2, D3. If the traffic becomes more congested (especially therefore in urban areas) or the road becomes more winding, the regenerative braking settings are available to the driver. The regenerative and thus the braking intensity increases across the four levels: D1, D2, D3 and B. When regenerative braking is used at level ‘D2’ or above the brake lights therefore automatically come on. For regenerative braking the electric motor changes into generator mode in order to be able to supply the recovered electrical power to the battery. In gear lever setting ‘D’ the driver simply taps the gear lever knob to the left to switch to ‘D1’ (1x), ‘D2’ (2x) or ‘D3’ (3x). Tapping the knob to the right moves down the D levels. If the gear lever is pushed to the right and briefly held there, the electronics switch in one jump back to ‘D’.

• B. In order to utilize maximum deceleration (40 kW at 100 km/h) in the ‘B’ setting (B = Brake), the gear knob needs to be clicked backwards towards the handbrake. If the driver’s foot is now taken off the accelerator pedal, he or she will feel the car slowing down as if the brake had been applied. In urban traffic with sufficient room ahead the car can be slowed to a standstill in this way. The fact is that drivers get used to the regenerative braking function very quickly and use it, above all in the ‘B’ setting, as a substitute for slowing down by applying the brake.

Charging. The simplest recharging option is to plug the charging cable supplied with the car into a conventional 230-volt socket. The battery is then charged from the grid at a power level of 2.3 kW. A completely depleted battery is recharged in this way within nine hours. As an option Volkswagen offers a wall box for the garage that charges the battery at a power level of 3.6 kW. The (completely flat) battery would thus be fully recharged after six hours. There are also public charging stations that ‘refuel’ electric cars at a power level of 3.6 kW.

As a new car the e-up! can also be prepared for the combined charging system (CCS) using a DC power supply. In this case it can alternatively be refueled via special CCS charging stations at power levels of up to 40 kW. The battery is then 80% recharged after just 30 minutes.

e-instruments. The e-up! comes as standard with the portable maps + more navigation system, complete with Bluetooth hands-free facility. In the e-up! it provides numerous new functions, such as range display (‘360° range’). In this mode a map of the surrounding region shows the radius of the area that can be reached with the current level of charge. Here too there are several different functions: ‘One-way range’ (route in one direction), ‘Range including return’ (route there and back) and ‘Combined’ (both range options).

Whenever a destination is entered into the navigation system the driver is informed (via a newly devised range warning system) whether the distance is possible with the current level of battery charge; if not, appropriate stops can be scheduled via the charging stations shown in the points of interest (POIs). A single, one-way route thus becomes a multi-stop route. Drivers are also able to save their own and new charging stations on the system and integrate these into their route planning.

Among the other maps + more functions and displays specific to the e-up! are the power flow and regenerative braking display and an e-manager. Using the e-manager, drivers can pre-program the charge start time and climate control pre-conditioning (switching on the parking heater in winter or parking air conditioning in summer for up to 30 minutes; if not plugged into a charger for up to 10 minutes). The advantage of having the car’s interior warmed up or cooled down while the battery is being charged (apart from the added comfort) is that you do not affect the battery’s charge level by any initial heating or cooling before starting up. As a result the battery’s full range is available at the start of the journey.

Using the ‘Car-Net e-Remote’ app it is also possible to make the most of these settings and information requests (air conditioning, battery charging, vehicle data and vehicle status info) via a smartphone or the Car-Net website. In detail the app contains the following functions:

Functions that are scheduled according to the programmed departure time include:

• Park heater/ventilation function; it is started at a specific time that depends on the outdoor temperature, so that the desired interior temperature is reached by the programmed departure time.

• Charging the battery: Starting and stopping the charging process, charging connection display, charge status, charge progress, charge level, charge time and range.

• Accessing vehicle data: Information display relating to individual journeys (single trips or long term), such as kilometers driven, journey time, electric motor power consumption, power consumption of other consumers such as air conditioning and radio, use of regenerative braking.

• Requesting vehicle status – Doors and trunk locked, lights (on/off), charging cable plugged in, battery charge level, range, position where the e-up! was last parked (GPS position on a map).

The e-Golf

The e-Golf. Click to enlarge.

The e-Golf also features low power consumption: 12.7 kW/100 km. Due to its overall technology; improved aerodynamics (cD = 0.281); and optimized rolling resistance, the Volkswagen is 10% more energy-efficient than the best steel-built direct competitor. After its spring 2014 launch in Europe, the e-Golf will roll out Asia and North America in late 2014 and early 2015, respectively.

e-motor and single-speed gearbox. The e-Golf is powered by an 85 kW/ 115 PS electric motor. From a standing start the synchronous motor, internally called the EEM 85, develops maximum torque of 270 Nm. The Volkswagen accelerates from 0 to 60 km/h within 4.2 seconds, and up to 100 km/h 10.4 seconds. Top speed is electronically limited to 140 km/h (87 mph).

The high-performance 12,000-rpm motor and single-speed gearbox (EQ 270), also developed by Volkswagen, with integrated differential and mechanical parking brake form a compact module. The motor/gearbox unit is made in Volkswagen’s components plant in Kassel, Germany.

Depending on route profile, driving style and payload, the driving range is between 130 and 190 km (81 and 118 miles); at very low outdoor temperatures, driving range may lie below these figures.

The e-Golf offers the option of a newly developed, optional heat pump. Offered as an add-on module for the electric heating (high-voltage heater) and the electric air conditioning compressor, the heat pump utilizes both the heat from the ambient air and the heat given off by the drive system components. In this way the high-voltage heater’s consumption of electric power is significantly reduced. Through use of the heat pump the e-Golf’s range increases in winter by up to 20%.

Lithium-ion battery. By virtue of the flexibility of the new Modular Transverse Matrix (MQB) on which the current Golf design is based, Volkswagen was able to integrate the lithium-ion battery in space-saving fashion within a stabilizing frame in the vehicle floor (under the front and rear seats and in the area of the centre tunnel). Like the motor elements of the powertrain, the battery was also developed in-house at Volkswagen.

The e-Golf has a curb weight of 1,510 kg (3,329 lbs), of which 318 kg (701 lbs) are accounted for by the lithium-ion battery. It is made up of a total of 264 individual cells, which are integrated into 27 modules (each with six or twelve cells). The cells add up to a nominal voltage of 323 V. Battery capacity is 24.2 kWh.

The battery is fitted at the front with a battery management controller (BMC), which performs safety diagnosis and monitoring functions and also regulates the temperature balance in the battery junction controller (the interface to the motor’s energy supply). When the car is not in use or in the event of a crash, power from the battery is automatically cut off.

Power electronics. A central element of the drive system is the power electronics module. Acting as the link, this module controls the flow of high-voltage energy between the e-motor and the lithium-ion battery (depending on battery voltage between 250 and up to 430 V). In the process the power electronics module converts the direct current (DC) stored in the battery into alternating current (AC). The power electronics therefore have the following interfaces: the traction circuit connection to the battery; the 3-phase connection to the e-motor; the plug connector from the DC/DC converter to the 12-V power circuit; and a connection for the high-voltage power distributor.

Charging. As with the smaller e-up!, there are several different ways of charging the battery in the e-Golf. As the conventional solution, the charging cable supplied as standard with the car is plugged into a 230-volt mains electrical socket. The battery of the e-Golf is charged in this way at a charge level of 2.3kW of alternating current (AC) from the mains. If it is completely flat, it will be fully charged again within a maximum of 13 hours. As an optional extra Volkswagen is offering a wall box for the garage or carport. This charges at a level of 3.6 kW. If completely flat (which in practice is rare), the battery would thus be fully charged again after around eight hours.

There are also public charging stations that recharge electric cars at a power level of 3.6 kW. The e-Golf can also optionally be prepared for the combined charging system (CCS) using a DC power supply. In this case the Volkswagen can be recharged via special CCS charging stations at power levels of up to 40 kW, allowing the battery to be charged to 80 per cent in around 30 minutes. On the e-Golf the start of the charging process can be activated—immediately or delayed by programming the time—by pressing a button next to the charging socket under the ‘fuel cap’.

Driving profiles and regenerative braking. Two technologies of primary importance in relation to optimal utilization of the vehicle’s energy are the two driving profiles designed for energy economy (‘Eco’ and ‘Eco+’) and the four different levels of regenerative braking (‘D1’, ‘D2’, ’D3, and ‘B’).

The e-Golf is equipped as standard with three driving profiles: ‘Normal’, ‘Eco’ and ‘Eco+’. The Volkswagen is automatically started in ‘Normal’ mode. For drivers wanting to extend the range, the first option is the ‘Eco’ mode. The effects of selecting this mode include paring back the e-motor’s maximum power output to 70 kW and the starting torque to 220 Nm. In parallel, the electronics reduce the output of the air conditioning system and modify the response curve of the accelerator pedal.

The e-Golf can now reach speeds of up to 115 km/h (in ‘Normal’ mode: 140 km/h) and accelerate from 0 to 100 km/h in 13.1 seconds (in ‘Normal’ mode: 10.4 seconds). In ‘Eco+’ mode the electronics limit the power output to 55 kW and the starting torque to 175 Nm. At the same time the accelerator pedal response curve becomes even flatter and the air conditioning is switched off. The e-Golf now reaches a top speed of 90 km/h and accelerates at a correspondingly slower rate.

Nevertheless, via kick-down—in ‘Eco’ and ‘Eco+’ mode—drivers can still obtain full power, maximum torque and a top speed of 140 km/h.

In addition to the driving mode function, the range can also be influenced using the regenerative braking system. As in the e-up!, there are five levels available: ‘D’ (no regenerative braking), ‘D1’, D2’, ‘D3’ and ‘B’.

In gear lever setting ‘D’ the driver simply taps the gear lever knob to the left to switch to ‘D1’ (1x), ‘D2’ (2x) or ‘D3’ (3x). Tapping the knob to the right moves down the D levels. If the gear lever is pushed to the right and briefly held there, the electronics switch in one jump back to ‘D’. The driver activates regenerative braking level ‘B’ by pulling the gear shift lever backwards. In an electric car this number of levels leads to a different way of driving. It is possible to use regenerative braking consciously to slow the e-Golf down.

Level ‘D1’ regenerates energy and slows down the car the least, while level ‘B’ has the strongest effect. At levels ‘D2’, ‘D3’ and ‘B’, the deceleration via regenerative braking is so strong that in this case the brake lights automatically come on. However, if the battery is fully charged, no energy regeneration takes place. In this case, the braking power also reduces, which the driver can feel intuitively.

Aerodynamics and rolling resistance. By developing very specific measures such as reducing the volume of cooling air (via a radiator shutter and partially enclosed radiator grille), new underbody panelling, modification of the tail with a rear spoiler and C-pillar air guides, and by developing new aerodynamic wheels (largely closing off the wheel openings flush with the car’s exterior), Volkswagen was able to lower the Golf’s air drag. Whereas on the standard Golf (1.6 TDI with 77 kW) air drag is 0.686 m², the company was able to reduce this to 0.615 m² on the e-Golf, thus improving it by 10%. Similarly, the cD value was improved to 0.281.

Volkswagen was also able to achieve another positive effect on energy consumption and range through optimization of the tires (205/55 R16 91 Q). Reducing the rolling resistance coefficient from 7.2 per 1,000 (Golf BlueMotion) to 6.5 per 1,000 for the e-Golf (likewise an improvement of 10%) also improves the range.

Acoustics. Electric drive systems present a challenge in relation to acoustics; the absence of any internal combustion engine very different sources of noise become noticeable. In addition, the scarcely perceptible and yet very specific background noise of the drive system is joined by the sounds and vibrations of the electrically powered auxiliary components. Last but not least, without any fine tuning, wind and rolling sounds are much more noticeable in electric vehicles, as they are in luxury cars.

Volkswagen implemented an acoustic concept for the e-Golf that is specifically tailored to the characteristics of an electric vehicle, making the zero-emission car into an almost silent cruiser. A few examples:

• The powerplant suspension system was switched to a pendulum mount with modified response characteristics, which despite the e-motor’s high build-up of torque when accelerating greatly enhances the acoustics.

• Through the design of the motor housing unit Volkswagen was also able to achieve an extremely low level of noise emission.

e-instruments. On the left-hand side of the instrument cluster the rev counter is replaced by the power display (which indicates if the motor is ready, the battery is being charged via regenerative braking or power is being drawn off) and the indicator of output availability. Still on the right as a corresponding instrument is the speedometer, in this case going up to 160 km/h.

Added to the bottom section of the speedometer is an indicator showing the charge level of the high-voltage battery. On the color display (premium multifunction display) between the power display and the speedometer, features now include a permanent indication of the driving range, of the currently active level of regenerative braking and an indication of the remaining charging time and of the type of charging connection. In a separate LED field in the lower segment of the multifunction display, the ‘READY’ message also appears after starting the motor, indicating readiness for the car to be driven.

Every Golf is equipped with a touchscreen. In the case of the e-Golf it is the range’s premium display, the top ‘Discover Pro’ radio/navigation system’s 8-inch touchscreen. In the e-Golf the system now shows numerous new functions.

• Range monitor: this provides a graphic illustration of the vehicle’s current range. The range potential of any auxiliary consumers is also displayed, as by switching off the consumer units shown to be on, the driver can gain extra range.

• Energy flow indicator: by means of animated graphics this depicts the energy flow when accelerating (blue arrows) and when applying the brake that involves regenerative braking (green arrows). Meanwhile, regenerative braking statistics provide information on the amount of energy recovered since the start of the journey.

• e-manager: this enables drivers to pre-program up to three departure and charging times. At the defined time the vehicle ensures the set air conditioning and battery charge level. The heating or cooling of the interior can also be activated via parking heater/ventilation (fitted as standard) during the charging process. The air conditioning process thus does not have any effect on the charging of the battery which extends the range.

• 360° range: the current radius of the e-Golf is shown by the so-called 360° range on the map of the surrounding area. The inner area represents the potential zone for a return trip. The outer area, on the other hand, represents the range for a one-way journey. Charging stations can be displayed and integrated into the route as intermediary destinations.

Volkswagen Car-Net e-Remote. Using the ‘Car-Net e-Remote’ app it is also possible to make many settings and information requests via a smartphone or the Car-Net website.

• Programming of the departure time: Functions that are scheduled according to the programmed departure time include the the park heater/ventilation function; it is started at a specific time that depends on the outdoor temperature, so that the desired interior temperature is reached by the programmed departure time.

• Climate control: Starting and stopping the auxiliary climate control function, plus display of the outside temperature and the target temperature for the car’s interior.

• Charging the battery: Starting and stopping the charging process, indicating charger connection status, charge status, charge progress, charge level, charge start time and range.

• Accessing vehicle data: Information display relating to individual journeys (single trips or long term), such as kilometers driven, journey time, electric motor power consumption, power consumption of other consumers such as air conditioning and radio, use of regenerative braking.

• Vehicle status queries: Doors and boot locked, lights (on/off), charging cable plugged in, position where the e-Golf was last parked (GPS position on a map).

The world of Volkswagen e-mobility

From the moment sales of the e-up! begin this autumn, around 250 specialized support operations in Germany alone will be providing people all over the country with information about the e-up! and all of the e-services that are available for the new model.

Anyone buying an electrically powered Volkswagen can order a charging facility along with the car: in cooperation with Bosch Automotive Service Solutions, Volkswagen is offering a complete package of wall box and installation.

With the box the high-voltage battery in the e-up! is 100% recharged at a power level of 3.6 kilowatts (kW) within just six hours. Interested customers can order the wall box from their dealer. After a site inspection by a certified electrician customers are given a personal quotation. Assuming they decide to go ahead, the wall box is delivered and professionally installed. The wall box plus installation pack is available from €820 (in Germany). The ultimate price depends on what work is necessary at the customer’s home.

For the launch of the e-up! Volkswagen in Germany is also offering electricity provided by hydropower plants in Germany, Austria and Switzerland. The company’s partners in this venture are LichtBlick SE (Hamburg) and Volkswagen Bank GmbH (Braunschweig).

‘BluePower’ can be ordered now from selected Volkswagen dealerships, from branches of the Volkswagen Bank and via the bank’s website. The tariff consists of a monthly base rate of €8.95 and a kilowatt/hour rate of 24.78 cents (both including VAT) and applies to the whole household supply. Customers switching to ‘BluePower’ receive a reward of €30 initial credit. The contract can be terminated at any time subject to a notice period of four weeks.

The electricity’s origin and quality comply with the strict criteria of the ‘ok power’ seal of approval from Energievision, an association sponsored by the Eco-Institute and North Rhine-Westphalia Consumer Advice. That means that at least a third of the electricity comes from hydropower plants that are no more than six years old. This ensures that further investment is continually being made in the generation of renewable energy and thus in climate protection and the switchover to new sources of power. The tariff is also certified by TÜV Nord.

In linking up with LichtBlick, Volkswagen has selected as its partner Germany’s largest independent energy supplier. LichtBlick sells electricity exclusively from regenerative sources and has received numerous awards for its products, value for money and customer service. The two companies already work together on the marketing of combined heat and power plants. Together with other partners they are investigating in the INEES research project (on ‘Intelligent integration of electric vehicles into the power grid for the provision of system services’) ways in which pooled electricity from vehicle batteries can be used to stabilise the power grid in Germany. Eco-power tariffs for other group brands are in the pipeline.

In order to offer drivers of the e-up! greater peace of mind on longer everyday trips as well, Volkswagen is offering another special e-service: if while still getting used to the new drive system technology drivers overestimate the range and the battery becomes fully drained, they can have the car towed free of charge up to two times to the nearest Volkswagen partner, a public charging station or their home.

Owners of the e-up! get a guarantee on the car’s high-voltage battery for eight years or 160,000 kilometers (99,400 miles). Alongside that the existing Volkswagen warranty/guarantee period of two years with no kilometer limit applies for all faults covered by the warranty. For paintwork defects an extended guarantee period of three years applies, while the anti-perforation guarantee is for 12 years.