Right then! How does this work. I travel 21 miles to work everyday. It breaks down like this

30mph for 2 miles

60 mph for 2 miles

70mph for 14 miles

30 mph for 3 miles

On the way to work - regardless of what time I leave, if I stick to the limits above (which I always do Officer:rolleyes: ) then I get 47.6 ish. However, on the way home I get 55.2.

My home is 182 ft above sea level and my work is 46 so that rules out the big hill theory. The only thing I can think of is that a cold soak overnight affects the fueling of the donk in the mornings. My mate lives at the beginning of the 70mph section, has the same car (but a 54 model), works at the same place and experiences the same thing.:confused:

However, I work a split shift thing so I do week of earlies, then a week of nights so I travel in at differing times (temperatures) so go figure?

Anyone got any similar experiences?

Cheers

Rossi

in theory the colder the engine the longer it will take to reach normal operating temperature and a cold engine is obviously less economic.

however the colder the air being taken in via the intercooler the more power is produced.

of course none of that explains your mystery, and yes i've noticed this in my vrs, proberbly is do with a lot of small things like gear changing, how much throttle, braking etc, for instance i believe that on the overrun modern cars use no fuel at all.

just to add that no matter what i always get 49 point something mpg to a tank of fuel, doesn't matter how i drive or where i go, except around the track where i get about 25:thumbup:

Hi,

I was perplexed by similar situation. To work and back 55 miles each way. Same journey times and similar traffic conditions. Constant difference between going (more economical) and returning (less economical) throughout year so temperature or using electrics more/less isn't the difference. Altitudes similar. Two factors seem important. 1. Wind - it's an W - E journey going so often prevailing direction important. 2. Slope on hills. A short steep climb and then fairly level seems more economical than a slow steady climb at same overall speeds. I guess it's something to do with the efficiency at certain rev/gear/accelerator position combinations. Intriguing.

If you're on an incline, 6th gear may not give you the best fuel economy.

6th also seems to have an interesting speed vs fuel economy thing going on, where if you are fairly low in revs it's good, if you go a little higher it drops, if you go higher up the revs (potentially into the territory where you are on the margin from getting pulled by a police officer were (s)he to spot you) it improves again.

Fuel economy varies based on so many factors however.

On the warming up thing - with the frost etc my aim is to clear that darn windscreen asap so I can drive the car. The only way to heat up the car relatively quickly is to rev it up to around 2k to get the turbo to spin up & produce a little heat. Still takes a little while even then though.

Then as soon as the windows are clear, get driving and make it work a little so the heat gets into that engine. Must admit I try to be sensible on 'planting it' until it's done a good few miles on the A34 now, so the engine can warm up a little