Mercedes-Benz C-Class Estate (S 205) 2014: C 300 BlueTEC HYBRID & C 250 BlueTEC. Click to enlarge.

The new Estate’s gasoline and diesel engines with ECO start/stop function comply with the Euro 6 emissions standards. All diesel BlueTEC models are equipped with SCR (selective catalytic reduction) technology, and cover an output range from 85 kW (116 hp) to 150 kW (204 hp).

In addition, Mercedes-Benz offers a diesel engine combined with a hybrid module. The C 300 BlueTEC HYBRID with four-cylinder diesel engine and compact electric motor generates a power output of 150 + 20 kW (204 + 27 hp) and despite its high power output runs on just 3.8 liters of diesel per 100 km (62 mpg US) in NEDC combined mode (equivalent to 99 grams of CO₂).

Three BlueDIRECT four-cylinder gasoline engines and one BlueDIRECT six-cylinder gasoline engine with power outputs ranging from 115 to 245 kW (156 to 333 hp) will initially be available for the new C-Class. The four-cylinder C 350 HYBRID with plug-in technology will follow in due course.

OM 626. The 1.6L OM 626 is the first standard passenger car diesel engine to use steel pistons. With reduced friction and better thermal behavior, these offer advantages in terms of fuel consumption and strength over aluminium pistons, which are state of the art today. The crankcase of the new diesel engine, which is characterized by low NVH properties, is made of grey cast iron, the cylinder head of an aluminium alloy. An overhead camshaft actuates two intake and two exhaust valves per cylinder.

Technical data for the OM 626
Cylinder arrangement/number	In-line/4
Displacement (cc)	1598
Bore (mm)	80
Stroke (mm)	79.5
Valves per cylinder	4
Cylinder spacing (mm)	88
Compression ratio	15.4:1
Rated output (kW @ rpm)	100 @ 3800
Rated torque (N·m @ rpm)	300 @ 2000

The common-rail direct injection system of the new small diesel engine operates at a maximum injection pressure of 1600 bar. Solenoid injectors and injection nozzles with flow-optimized hole geometry deliver low emissions and quiet operation.

The new diesel engine is the product of the strategic cooperation with Renault. It is produced by Renault and assembled in part in Bremen. Technology modules specific to Mercedes-Benz make the engine more efficient. They include the ECO start/stop function; the ancillaries; and a special dual-mass flywheel that better compensates the imbalances that are characteristic of diesel engines and makes a balancer shaft unnecessary. The engine control unit with additional functions ensures Mercedes-style driveability.

The BlueTEC diesel engines. In addition to the new small diesel engine, an advanced version of the 2.2-liter four-cylinder diesel engine is also available in several output variants. The diesel engines will thus cover an output range from 85 kW (116 hp) to 150 kW (204 hp).

All diesel engines are equipped with SCR (selective catalytic reduction) and ensure that the models with diesel engines attain at least efficiency class A, and in most cases even efficiency class A+. The models with 4MATIC all-wheel drive are the exceptions.

Hybrid with four-cylinder diesel engine. In addition, Mercedes-Benz offers a diesel engine combined with a hybrid module. In addition to the combustion engine and the electric motor the hybrid module of the C 300 BlueTEC HYBRID includes the 7G-TRONIC PLUS transmission, combined power electronics with DC/DC converter and a high-voltage lithium-ion battery. It has a high energy density and is consequently particularly suited as a storage medium for the electric energy generated by the electric motor.

An additional conventional 12-volt battery is installed in the multifunction recess in the rear of the hybrid model. It powers all standard consumers and the high-voltage components.

The diesel hybrid model is furthermore equipped with an electric vacuum pump and a braking system for effective energy recuperation custom-developed for the hybrid. An electric refrigerant compressor ensures the automatic climate control system also works when the combustion engine is switched off. This technology makes pre-entry climate control of the vehicle possible to ensure pleasant interior temperatures already when getting into the vehicle.

With its compact components, the hybrid technology is fitted in the standard installation spaces without restricting the load compartment volume.

The hybrid offers silent start and electric driving for a limited distance at speeds up to about 35 km/h (22 mph). The vehicle also offers three sailing modes:

• Sailing in “C” (Comfort) mode: the vehicle coasts with the engine switched off. If the driver releases the accelerator at speeds below 140 km/h (87 mph), the combustion engine is decoupled and switched off—the vehicle enters sailing mode. In the process the electric motor generates overrun torque through energy recuperation so that the vehicle coasts and decelerates like a conventional vehicle. The recuperated energy is stored in the high-voltage battery and is available for boosts and electric driving.

• Sailing in “E” (Eco) mode: energy recuperation is reduced to a minimum. While the combustion engine remains switched off, only a small amount of the energy is used through recuperation to cover the requirements of the on-board electrical network. Instead it provides a higher coasting speed and/or longer coasting distance—an advantage on longer downhill stretches and in approaching traffic lights and junctions with foresight.

• Sailing PLUS: this function is activated in sailing mode with the right-hand steering-wheel gearshift paddle. It reduces, as in the “E” mode, energy recuperation to a minimum.

In addition to its boosting and energy recuperation functions, the electric motor dampens torsional vibrations in the powertrain and consequently increases ride comfort.

A further hybrid model (C 350 HYBRID), due to follow six months later, will be powered by a 4-cylinder gasoline engine and feature plug-in technology.

The gasoline engines. Three BlueDIRECT four-cylinder gasoline engines and a BlueDIRECT six-cylinder gasoline engine developing 115 to 245 kW (156 to 333 hp) will also be available. The four-cylinder C 350 HYBRID with plug-in technology and a power output of 155 + 60 kW (211 + 82 hp) will follow in due course.

The BlueDIRECT gasoline engines combine spontaneous response and strong power delivery with high efficiency and best-in-class emissions. The engineers have developed the technology further into third-generation direct gasoline injection with spray-guided combustion. The system pressure is up to 200 bar, the pressure being variably optimized according to the engine’s mapping. Piezo injectors enable optimal mixture formation with up to five injections per power stroke. The third-generation direct injection is supplemented by rapid multi-spark ignition (MSI). The result of this is excellent utilization of the fuel with minimum emissions.

The thermal management is also efficient: when the engine is cold, no coolant runs through the engine due to an on-demand water pump. As a result, the combustion chambers heat up more quickly after starting up the engine. The thermostat is electronically controlled and the coolant temperatures are adjusted according to driving style and ambient conditions. In the interest of high efficiency, the volumetric flow of the oil pump is likewise controlled as in the V engines. All engine variants are designed for operation with E10 premium gasoline and an octane rating of 95 RON.

Since the Estate engines are up to 20% more fuel-efficient than those in the outgoing model—new fuel consumption as low as 5.4 l/100 km (43.6 mpg US)—the fuel tank has been reduced to 41.5 liters (11 gallons US) despite the comparable range (C 250 and C 250 BlueTEC 66 liters). A 66-liter (17.4 gallon US) tank is also optionally available for the other models.

ECO start/stop function with direct starting as standard. The ECO start/stop function included as standard in all models operates with starter motor-supported direct starting. This means that when the engine is switched off, the angle of the crankshaft is registered by a crankshaft sensor so that the engine control unit knows the positions of the individual cylinders. On restarting, it can then select the cylinder that is in the most suitable position for first ignition. After the starter has briefly turned over the engine, reliable injection, ignition and combustion is immediately possible in the ideally positioned cylinder.

Optimized powertrain. Mercedes-Benz offers a new 6-speed manual transmission for the four-cylinder engines in the new C-Class Estate. It features enhanced ease of shifting coupled with increased shifting precision and a harmonious gear change sequence. Dry sump lubrication and improved low-friction oil enable comfortable gearshifts even after a cold start.

Smooth automatic gearshifts are provided by the 7G-TRONIC PLUS automatic transmission with DIRECT SELECT lever and DIRECT SELECT gearshift paddles, which has undergone further development at Mercedes-Benz. Among the traits of the latest evolutionary stage of the 7G-TRONIC PLUS are the new torque converter with reduced slip, an ECO transmission mode with improved gear spread as well as an auxiliary oil pump that maintains the operating pressure when the engine is automatically switched off. Friction-optimized components in conjunction with low-friction oil make it possible to lower the operating pressure.

A new feature is Momentary M mode. The benefit of this is that if the driver has shifted up or down manually, the transmission independently switches back to fuel-efficient automatic shift mode after a set period of time. This period of time is extended under specific conditions (no accelerator pedal use, e.g. on downhill gradients, high lateral acceleration, e.g. when cornering, or if the speed falls below a minimum threshold when coming to a stop), preventing the return to automatic mode.

In Momentary M mode as well as in “fixed” M mode, the driver will receive gear change recommendations in the multifunction display of the instrument cluster, to enable an efficient driving style.

Mercedes-Benz Intelligent Drive. The Estate adopts new assistance systems from the S-Class and E-Class, which have been enhanced with significant functions. The assistance systems enhance both comfort and safety. Mercedes-Benz calls this Intelligent Drive.

The C-Class Estate is fitted as standard with ATTENTION ASSIST, which can warn the driver of inattentiveness and drowsiness. It offers an adjustable sensitivity level and can provide drivers with information on their level of fatigue and the amount of driving time that has elapsed since the last break. On motorways ATTENTION ASSIST in conjunction with COMAND can suggest service areas as stopovers where a warning has been issued.

Also part of the standard equipment is COLLISION PREVENTION ASSIST PLUS. In addition to the distance and collision warning as well as the adaptive Brake Assist, which helps to protect against collisions at speeds above 7 km/h (4.3 mph), this system now features an additional function: when a danger of collision persists and the driver fails to respond, the system is able to carry out autonomous braking at speeds of up to 100 km/h (62 mph)—200 km/h (124 mph) in conjunction with DISTRONIC PLUS—thereby preventing a rear-end collision with slower or stopping vehicles or reducing the severity of the resulting collision. At speeds of up to 50 km/h (31 mph) the system also brakes in response to stationary vehicles, and is able to help prevent rear-end collisions at up to around 40 km/h (25 mph).

New assistance systems with substantially enhanced functions are optionally available, combining data from various sensor technologies as part of the Intelligent Drive concept to enhance comfort and safety:

• DISTRONIC PLUS – relieves the burden on the driver in keeping a safe following distance.

• DISTRONIC PLUS with Steering Assist and Stop&Go Pilot – relieves the burden on the driver in keeping a safe following distance, even in stop-and-go traffic. Steering Assist is new and helps the driver with lateral control of the vehicle, even in gentle bends, and offers a tailback vehicle following function.

• BAS PLUS with Cross-Traffic Assist boosts driver braking depending on the situation, if necessary up to full brake application and can also react to crossing traffic and pedestrians.

• Active Lane Keeping Assist warns of unintentional lane departures by means of pulsed vibrations of the steering wheel and in the presence of solid lane markings corrects the vehicle’s track with one-sided brake application. It now also intervenes with one-sided brake application in the presence of broken lane markings if the adjacent lane is occupied by, for example, oncoming traffic, fast overtaking or overtaken vehicles.

The multitude of optionally available assistance systems also include, among others:

• Active Parking Assist, which enables automated parking with active steering and brake control in both parallel and end-on spaces, as well as maneuvering out of parallel spaces again if the vehicle was parked there automatically beforehand. Traffic Sign Assist with wrong-way warning function, which warns of speed limits and also alerts the driver to no-overtaking zones and no-entry signs.

• Adaptive Highbeam Assist PLUS, which allows the high-beam headlamps to be kept on permanently by masking out other vehicles in the light cone of the high-beam headlamps.

Air conditioning: tunnel detection via satellite navigation. The further advanced climate control system provides improved control quality, performance, efficiency and air quality. The new Estate is the only vehicle in the segment to offer tunnel detection via satellite navigation. It uses the map data from the navigation system and the GPS location data to close the air recirculation flap automatically when the vehicle enters a tunnel, subsequently re-opening it when the vehicle emerges from the tunnel.

Another highlight contributing to a feel-good atmosphere is the AIR-BALANCE package with active fragrancing, air ionization and more efficient filtration than is available on the standard model.