Noticed that my fuel consumption is around 2mpg lower than normal compared to this time last year.

 

I don't have any warning lights, tyres are at the correct pressure, regularly serviced etc etc.

 

Anyone know what it could be or i could do?

alignment out?

Was the weather not slightly different at this time last year, warmer actually. ?

4 wheel alignment done 600 miles ago with brand new tyres too.

 

Currently getting around 28mpg and that's mixed driving. Was on the bypass the other day with the cruise control on at 60mph and was only getting around 40mpg instead of around 48mpg.

 

Had the car for 15 months and always had over 30mpg per tank and my last time was 28.8. Current tank is onl 28.2 after 60 odd miles.

So are they identical new tyres to those that were on last year, or different brand, and slightly different total diameter,

enough different to give 2 mpg difference?

(ie, measure side by side with the tyres removed.)

 

http://kouki.co.uk/utilities/visual-tyre-size-calculator

Same size of tyres. Got Goodyear Eagle F1s which replaced the Continental Sports that came with the car,

Do you mean same size on the tyres, as in the markings 225/45 R17 ?

 

That does not mean the same size, which is why i said you need to measure side by side.

 

I have Dunlop Sport Maxx 205/40 R 17  

& Pirelli Zero Nero 205/40 R 17, & the Pirelli are physically bigger than the Dunlops and the same size as my 215/40 R 17 Wet Weather Tyres.

 

The difference in Brand, Tread, Compound and size can be 2 mpg.

Yeah they are the same 225/40/18. Just the same as standard but different tyres which have a better fuel rating.

Maybe better rating on the label, worse economy in the real world.!

 Time will tell if the car is running as was otherwise.

Prob the temp, it's a fair bit colder this year than last. Wind can also make a fair bit of difference.

 

Could even be road conditions, traffic, crap in the boot new road layout. 2mpg isn't much of a change.

It's all about winter time...engine operating temperature is reaching slower, blower motor revs faster,headlights are used longer, rear windscreen heater,seat heating etc. That all is extra load for alternator. 

 2mpg is peanuts,there is nothing to worry about!

A change of shoes could even make 2mpg of difference. Got big boots on this year?

Edited 21 January, 201511 yr by Aspman

How much miles on the car? You considered a terraclean?

My CR vRS is down about 8 or 9mpg on what it gets during the summer, thats a mix of stop start (Edin City Bypass) and Motorway.

I assumed winter was killing it, cold engines only just gets to 90deg oil temp as I get to work, and heated seats on all the time!