I went from Guildford to Bury St Edmonds yesterday; about 125 miles each way. I drove similarly in each direction and the traffic was about the same.

Yet on the way there I got 57mpg, and on the way back I got 49mpg.

This morning on the way to work I was back up to 55mpg, so it's not something borked on the car.

Any ideas how I could get such different figures? As I say, traffic was about the same each way, and I was driving at the same sort of speed. Maybe it's all downhill on the way there. :confused:

Air temp I find has a lot to do with MPG. It's better in warmer air but the car feels slightly flatter due to it being less dense.

Also, could be a subtle incline on the way back...the throttle may need to my sliiiiiightly more depressed to keep the same speed.

Could be slightly downhill/uphill/windy in one direction....???

I think it was marginally warmer on the way back. The weather was about the same too; no aircon either way (I gather that uses a bit more fuel). Lights on the way back, but I can't see them making that much difference?

I think a general up/downhill thing is most likely, as you've both said. Still struck me as strange!

I think it was marginally warmer on the way back. The weather was about the same too; no aircon either way (I gather that uses a bit more fuel). Lights on the way back, but I can't see them making that much difference?

I think a general up/downhill thing is most likely, as you've both said. Still struck me as strange!

when you were in bury... did you do much town driving? the a14 is a great road... bury town centre is a bit, well, naff to drive in... (lived there for 16 years!)

Not much, no - drove in, went to a school, did a videoconferencing demo and came home. Bit of a waste of 6 hours and £20 of diesel!

Not much, no - drove in, went to a school, did a videoconferencing demo and came home. Bit of a waste of 6 hours and

The wind also plays a big part. I drove to Tiverton the other week, got 46MPG there as I was driving into a headwind and 57MPG back.

I think it was windier on the way there. Though that was crosswind, whereas I suppose I'd not have noticed a headwind.

The school was St somethings-or-other. Began with a B. Catholic place. I'd forgotten what schools smell like.

I think it was windier on the way there. Though that was crosswind, whereas I suppose I'd not have noticed a headwind.

The school was St somethings-or-other. Began with a B. Catholic place. I'd forgotten what schools smell like.

St benedicts.... grove park road -

i went to the one over the road!

That's the one!

It was a bit overkill really. One engineer from Bristol (400+ miles), me from Guildford (250 miles) and the sales manager from somewhere around Richmond (200 miles).

So something approaching 900 miles travelling in total. What a waste. Still, I get £100 in petrol money for it.

I went from Guildford to Bury St Edmonds yesterday; about 125 miles each way. I drove similarly in each direction and the traffic was about the same.

Yet on the way there I got 57mpg, and on the way back I got 49mpg.

This morning on the way to work I was back up to 55mpg, so it's not something borked on the car.

Any ideas how I could get such different figures? As I say, traffic was about the same each way, and I was driving at the same sort of speed. Maybe it's all downhill on the way there. :confused:

Very likely was the wind. Drag and hence the required force to sustain speed goes up with the square of velocity (velocity for that matter is your speed on the road + the speed of the wind). Just a slight headwind drives up your fuel consumtion as if you'd be driving a lot faster. And there you wouldn't be surprised about low MPG readings.

I regularly get that effect between Cambridge and Norwich where westerly winds prevail.

Michael

That does all make sense. After all, I'd normally expect about 53mpg - 57 is doing very well in my experience.

Still, I get

I always get the same, 50MPG on my wat to work (about 50 miles!) and 55MPG on the way home.

just don't put petrol in

But petrol cars are faster!

Has anyone noticed the effect which outside temperature has on fuel consumption? I recently drove my Fabia 1.9 TDI on the same 60 mile route in similar traffic conditions and on the same tank of diesel. Apart from the temperature, the weather conditions were similar and I don't think that my driving was much different. The first journey, when the temperature was reading about 3C, gave a computer read out of 62.5 mpg. The temperature on the second journey was about 9C and the fuel consumtion read 72mpg.

The other thing I have noticed is how much the fuel consumption has improved with mileage. This car has now covered over 60k. Until it had done about 40k I never seemed to get a fuel consumption averaging over 58mpg.

The colder the intake temperature the greater the amount of fuel injected!

Hence the higher comsumtion figure!

In my case, it all seems to be down to altitude. On the way to work, I get 60+ mpg, on the way home, I'm lucky to see more than 52-53 mpg. After puzzling about it for a while, I checked - work is 219 feet above sea level, home is 564 feet.....

Paul.

In my case, it all seems to be down to altitude. On the way to work, I get 60+ mpg, on the way home, I'm lucky to see more than 52-53 mpg. After puzzling about it for a while, I checked - work is 219 feet above sea level, home is 564 feet.....

Paul.

I'm the other way round. I struggle to see 50mpg on the way to work, can easily get 70+mpg on the way home. I know it's on a hill though. I've been trying to bike it a few times in the past couple of summers and it takes me 45 minutes to get to work but only 30 to get home.

I drive 5 miles to work - each end is approx the same height about sea level (about 5m) - I always get better MPG coming home in the evening...