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

Why is my fuel economy 7mpg less in winter?

Why is my fuel economy 7mpg less in winter? Since the weather has got colder, my fuel economy has got a lot worse. From an average of 43mpg in summer, I’m now only getting 36mpg. Apparently it shouldn’t drop by more than 3mpg, at most, because of the cold. Is that correct?

The temperature gauge slowly rises to just under half way, stays there and never wavers. The heater does get quite hot, but never that hot. It has been suggested that this big drop and poor mpg could be caused by a faulty thermostat. Would the diagnostic computer not have spotted this? Do you think this could be the problem? It’s going to cost me £170 for the garage to replace, which I don’t want to pay if I don’t have to.

Asked on 25 January 2018 by Iain Buchanan

Answered by Honest John
Depends how far you regularly drive the car and therefore how much of your motoring is on enriched mixture and how much is on normal mixture. If you are regularly driving 20-mile journeys then fuel economy should not be more than 2-3mpg worse in winter. But if most of your runs are short, then it could easily be 7mpg worse.
Similar questions
I have the new Skoda Karoq 1.0 DSG. It's a lovely little car that drives well, even the DSG is amazing. However, I've done around 1200 miles and I can't get above 30mpg. The dealer said it's going to get...
Why do summer and winter mpg figures vary?
I currently own a 2003 Audi A3 1.8 and I'm looking to buy something that'll be cheaper to run. I'm considering getting a MINI, but which model can I get for under £2000? Is it likely to save me money,...
Related models
Easy to drive and refined. Very well built. Five-year warranty as standard. Neat and tidy styling. Decent room in the back seat. Good economy from entry-level 1.2-litre.
 

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