Mercedes is finally responding the BMW’s lead in reducing CO2 emissions with the introduction of three new fuel-efficient C-class models at the Geneva show. Dubbed “Blue Efficiency”, they use clever technology to dramatically cut fuel consumption and emissions. Both petrol and diesel versions will get the “Blue Efficiency” treatment; the C180 Kompressor, C350 CGI and C200 CDI.Most impressive of all is the C200 CDI Blue Efficiency. Powered by Mercedes-Benz’s 2.2-litre four-cylinder common rail diesel with 134bhp and 199lb ft of torque, it boasts combined average fuel consumption of 55.4mpg and a CO2 rating that betters many superminis at 135g/km (standard model: 46.3mpg and 149g/km) while possessing 0-62mph acceleration in 10.4sec and a 137mph top speed.Weight has been saved with a thinner windscreen, less sound deadening equipment and thinner, lighter alloy wheels shod with low rolling resistance tyres. The co-efficient of drag has been trimmed from 0.27 to 0.25 by blanking off part of the grille, sealing the joints around the headlamps and fitting more aerodynamic door mirrors. The C180 Kompressor Blue Efficiency gets a smaller capacity 1.6 litre engine (although it keeps the same model nomenclature), but keeps the same power and torque figures. Consumption improves by 7.3 mpg over the standard C180K to 43.5mpg with CO2 emissions reduced from 177 to 156g/km. The C350 CGI Blue Efficiency has a new direct-injection 3.5 litre petrol V6 with 289 bhp and 269 lb/ft of torque. It’s claimed to return 33.6 mpg and put out 220 g/km – outside the dreaded band “G” for emissions. Despite that, it hits the 0-62 mph benchmark in just 6.2 seconds and has an electronically limited 155 mph top speed. The models make their debut at the Geneva show and form the vanguard of a programme that will being up to 20 Blue Efficiency models within the next 12 months. But don’t get too excited – there are no current plans to bring them to the UK.