Noticeable drop in MPG (BWA engine)

[Rob.]

I noticed the other day that my car seems to have dropped in fuel efficiency lately.

I do a couple of journeys that would always average 39-41mpg (cruise control set at 70mph on the motorway). However, I can't seem to get over 35mpg, even with a light right foot.

I switched from 18"s with stretch back to the stock 17"s (with new Hankook Ventus), but that's the only thing externally that's changed.

Is there anything engine wise I should look at, or be worried about?

Thanks

[garrardrj]

My ED30 always did less mpg in the cold weather.

[AJP]

I get marginally less in the cold too.

The tyres on the 17s could well be playing a part as well. I suppose all you can do is check their pressure (try 34/35psi if they're much less) and try and get a scan done, see if there's anything going on with the engine.

Also, if your 18" wheels and tyres were lighter than the 17s you'd expect a slight drop in mpg moving back to the 17s. Probably unlikely though.

[Lewo]

I usually average around 33 but the last couple of fill ups in colder weather around 31.

[lukemk5gti]

I do the exact same drive on a daily basis to work. During summer I cant get 41mpg and during winter it can be as low as 31mpg.

Other factors include more people on the road etc. but for the most part the cold does decrease mpg.

I also believe that if either your main thermostat or inline thermostat are bust that it can decrease mpg? Usually this issue only comes to light in colder winter months when you see the temp not reaching 90.

I replaced my main thermostat and noticed an increase in mpg, one year later my inline thermostat went and I think it's causing a drop in mpg once more.

[reidy-]

exactly the same, 37-42 during the summer, 31-36 during the winter

looks pretty normal across the board, I was thinking it was my slightly sticking caliper!

[Rob.]

I knew colder air = denser charge = more power, but I sort of assumed it would be nearer 1-2mpg!

[shoaybmakda]

And here's me with my daily commute to work achieving 21mpg at best! - although most of it is city driving and a lot of stop start involved for about 6 miles only

[Optimistictim]

And I thought my 25mpg was bad for commuting. I feel for you!

[Mark_DF05]

I've noticed a significant drop in mpg over the last couple of months too. At first I thought it was down to the colder weather but I'm not too sure now.
 
On my 25 mile commute which is a mix of town driving and dual carriageway I'm getting around 29mpg whereas before I'd be getting 34/35. Only thing that's changed are 2 new rear tyres(eagle f1s).

There aren't any signs of a sticking caliper but I've noticed it taking arouund 15 minutes to warm up, is this normal?

I'm happy with the fuel economy but it's bugging me now thinking that something could be wrong.

[Rawhide]

I have just bought an ED30 and am getting similar and was expecting slightly better.

I am wondering if my thermostats are stuck open.  As it's new I don't know what to expect

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[golfmck1980]

Be thankful i think im doing well getting 27mpg atm