What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks

Is it credible that the new Mercedes-Benz CKS 350 petrol returns 40mpg?

I was surprised by the fuel consumption claim of 40mpg combined for the new Mercedes-Benz CLS 350 petrol model. I think the old model 320CDI was 36mpg combined (37.2mpg on 245 rear tyres). I have a 5-year-old 350 petrol, which had a combined claim of 29mpg that is only achievable on long motorway runs. I am aware that much work has been done to improve the economy of petrol engines but is this credible?

Asked on 5 March 2011 by PJ, Wendover

Answered by Honest John
No. All it means is that they stuck it on a chassis dynamometer that replicated the EC driving cycle and managed to achieve the equivalent of 40mpg in the EC combined cycle. Whether a real person can really achieve that in real life is another matter entirely. That said, over 692.3 miles in a Jaguar XJL 3.0V6 diesel I recently averaged 41mpg at an average speed of 58mph, and that is better than the official combined figure of 39.2mpg. For a better idea of the true fuel economy of recent cars, consult and participate in the Real Life Fuel Economy Register at: www.honestjohn.co.uk/realmpg
Similar questions
I recently bought a secondhand 2009 Insignia 2.0 CDTI SE to replace my 2001 Toyota Avensis 1.8 VVTI. I hoped to improve fuel economy with my change in car. The Insignia, which is a diesel, has only just...
I have a Vauxhall Insignia and all seems mechanically sound with 68000 miles on the clock, a recent service and full service history plus new discs brakes all round. When I bought it I was getting around...
I am looking to purchase a 3-4 year old car. What is the best petrol vehicle that provides 55 miles to the gallon?
Related models
More engaging to drive than German rivals. Characterful. Diesel is very strong. Excellent overall refinement.
Big CO2 reductions. Four-cylinder CLS 250 CDI available at last. Precisely-built interior. Retains unique style of original CLS. Comes with full LED headlights.
 

Value my car

Save £75 on Warranty using code HJ75

with MotorEasy

Get a warranty quote

Save 12% on GAP Insurance

Use HJ21 to save on an ALA policy

See offer