Renault's Megane will dip under the 100g/km CO2 barrier early next year thanks to a new diesel engine, the firm has revealed.
The new engine is one of a two new 'Energy' motors - one diesel, one petrol - announced at the Frankfurt motor show.
The petrol motor, called Energy TCe 115, is a 1.2-litre turbocharged unit producing 112bhp and 140lb ft; 90% of the torque is available from just 1500rpm.
Renault claims the unit gives 25% better fuel economy than the engine it replaces. It will be rolled out in the Megane and Scenic models in the first half of 2012.
Its also part of a modular family of engines; a three-cylinder, 900cc version, producing 89bhp, is already being lined up for Twingo and the next generation of Clio.
The diesel engine, called Energy dCi 110, has 108bhp at 4000rpm and produces 192lb ft of torque. In the Megane - the vehicle chosen for its debut - it will deliver 70.6mpg and CO2 emissions of 99g/km. That will be a crucial addition to the Meganes line-up, given that key rivals like the Ford Focus, VW Golf, Vauxhall Astra and new Hyundai i30 all offer variants that can beat the CO2 benchmark.
The only eco trick contributing to the cleaner Megane will be stop-start, however; specially altered gear ratios or low-rolling-resistance tyres will not be required to achieve the tax-busting figure.
Renault has yet to confirm precise dates for the engines' debuts, but they could tie in with facelifts for the entire Megane, Scenic and Grand Scenic range; all of those models are due for a mid-life refresh in 2012.