Mpg advice help (sorry) mines rubbish

[E30Dom]

Also, ignore the computer... it's always out... Mine showed 32mpg last fill up, but worked out i was getting closer to 35mpg...

[vRS_Pagey]

So why does mpg improve in the summer?  I understand that when intake temps are low performance is improved, is that the reason.......?

[E30Dom]

Air is less dense, therefore uses less fuel to mix with it...

[sub39h]

So why does mpg improve in the summer?  I understand that when intake temps are low performance is improved, is that the reason.......?

If you look at it the other way, why do you get worse mpg in the winter?

Because if the air is denser you get more oxygen and hence better performance, meaning you need less throttle suggesting you'll get better fuel mileage in the winter but this isn't the case.

The reason is multifactorial. Mainly:

1. Longer time to get to operating temperature
2. Use of more electrical equipment: air con; heated rear screen; heated seats etc

Those are probably the biggest two factors.

[vRS_Pagey]

Thanks for clearing that up guys! 

[ub7rm]

Its all to do with the warm up IMO.  On a short winter journey the MPG is noticably less than the same in the summer but on a longer journey I haven't noticed much difference at all. 

Colder air makes for better (more efficient) combustion but as said the longer heat up time and extra load on the altenator takes away from that. effect.

[marcus]

The best I've had on my 58 mile commute (M40/A34/M4) is 43.  This was driving to the speed limit and without using cruise in September, so mild weather.

I replaced the rears for 2 new Avons recently and I couldn't better 35 in colder weather