The Worldwise Harmonised Light Vehicle Test Procedure (WLTP) has been designed to provide more realistic testing conditions to calculate vehicle fuel consumption and emissions.

The driving cycle is divided into four sections with different average speeds: low, medium, high and extra high. Each section contains a variety of driving phases, stops, acceleration and braking phases. For each new vehicle type, every powertrain configuration is tested under the WLTP for the car’s lightest and heaviest variants.

Honda has made significant improvements to the engine and the exhaust system to maximize real world performance. The efficiency enhancements for the new Honda Civic 1.6 i-DTEC result in fuel economy and CO₂ emissions starting from 3.7 l/100 km (63.6 mpg US) and 99g/km (under the WLTP cycle).

The improvements to the 1.6-liter diesel include a reduction in cylinder friction, due to pistons made from highly durable chromium-molybdebnum steel alloy, as well as super plateau honing of the bores to enable smoother piston movement.

The 1,597cc engine uses the same advanced Bosch fuel injection system as before, and features a small, high-efficiency turbocharger, low-pressure EGR (exhaust gas recirculation) system and a high-intake flow, high-swirl cylinder head port.

A high-strength, lightweight slender crankshaft and all-aluminium, open-deck, high-pressure, die-cast engine block minimize the engine’s weight. For the new i-DTEC, additional cast ribs have been added to the cylinder block to increase structural rigidity and, consequently, improve the management of noise, vibration and harshness.

Honda’s new 1.6 i-DTEC is also one of the first engines to be officially tested through the Real Driving Emission (RDE) procedure to validate NO_x and particulate emission levels. The diesel powertrain has a new NO_x Storage Converter (NSC) system with larger catalysts and a higher content of noble metals (silver, platinum and neodymium) that store nitrogen oxide gas until the regeneration cycle. A soot sensor accurately detects when the regeneration cycle is required, extending exhaust component durability.

Real Driving Emission (RDE) tests measure the pollutants such as NO_x emitted by cars while driven on the road. RDE will be run alongside current NEDC and future WLTP test cycles as a validation process. RDE ensures the delivery of low emissions from vehicles during on-road conditions throughout Europe.

The RDE test is performed as part of emissions type approval on public roads in real traffic, using a Portable Emissions Measurement System (PEMS). Initially, only NO_x and particulate number emissions are included in binding limits. The initial diesel RDE limit for NO_x is 168 mg/km, which comes into force on 1 September 2017 for new vehicle types.

The 1.6 i-DTEC engine produces 120 PS at 4,000 rpm and 300 N·m of torque at 2,000 rpm, powering the Civic from zero to 100 km/h (62 mph) in 10.4 seconds.

Assembled at Honda of the UK Manufacturing in Swindon, the revised engine will be available in both the four-door and five-door variants of the new tenth-generation Civic.

A nine-speed automatic transmission will further bolster the Civic’s powertrain options in mid-2018, representing its first application in a two-wheel drive car.