Fuel Economy Query

[colwill197]

Hi All,

I have noticed recently my fuel economy has dropped slightly. So I looked into it. It started at 31mpg crusing at 70 with cruise control. So I pumped my tyres up to 32 psi. This helped and it is now at 33 ish. But I used to get atleast 35. What could have caused this? I did change to dunlop Sportmaxx could that have done it? I highly doubt it. Then had the idea it could be thermostats or temp sensor being out? Could it be one of these? I have checked my exhaust and by other people and I can confirm it is not this. So any advice really.

I have it booked in at 519 for belt change so if it is anything I or they can check please let me know.

Thanks for your feedback

 

[zuki]

Cold weather can effect fuel consumption, cold dense air needs more fuel
You've probably noticed an increase in performance too?

 

[colwill197]

this is motorway runs though. surely not 3-4 miles less.

 

[Foxspeed]

colder overall temperatures and running that bit longer to get to temperature...can have a noticeable effect on mpg

 

[Matt W]

Winter does this. The fuel mixture gets changed by the fuel companies for winter too iirc.

 

[Gez]

I've gone from 35-36 down to 29/30

 

[colwill197]

I've gone from 35-36 down to 29/30

So have I. Is that over the last few weeks/ maybe month or so. I thought it was my car :/

 

[Gez]

Yes, last 3-4 weeks it's dropped.

 

[Paddy_R]

Are the tyre pressure not higher than 32 in the front tyres. From memory 34 up front and 31 at the rear are the recommended pressures from Renault.

 

[Gez]

I run semi slicks, I've been running 31F 28R, now the winter has set in and I can't get the tyres up to temp, I'm running 34F 32R, so I've used the tyre pressures to compensate, still dropped in mpg.

 

[colwill197]

Recommended pressure depends on driving style. For motorway it says 34 yes.

 

[Robo_#1]

It's 35/35 for Motorway I thought.

Have you checked your brakes recently? It's possible you've got a sticky pad/caliper. That will easily cause a MPG drop. I've noticed my MPG go up after stripping/cleaning mine in the past (if I've been a bit naughty and left them too long between cleaning)