So, last week I drive into work, sensible use of loud pedal but not going overboard and get an amazing 57mpg - from a 07 VRS PD170 manual hatch.

Today, I drive the same route and was really trying hard to get the best mpg possible - but only managed 49mpg! Average over the last 600 miles is 48mpg across a mix of driving at various speeds.

The only variable I can think of is a fill up with Shell Fuel Save, not sure what was in it before but can't imagine it's the fuel that makes that difference.

Does anyone else get this? I've seen similar varience at times with my wife's Mk1 Fabia VRS too.

Yup I also have had this, recently a lot of Air con has made a difference and also driving in to the wind etc.

I can vary from 54 to late 40's on the same road etc.

Try resetting over just one stretch of road, eliminating stop and start before you get underway on a decent run.

Today drove as usual on my east west (into the wind usually) commute and got my best ever indicated mpg of 51.4. If I try to drive economically I tend to get 48mpg.

The only thing I can think of is I was in a gear or two lower than usual, for some of the trip.

Yup I also have had this, recently a lot of Air con has made a difference and also driving in to the wind etc.

I can vary from 54 to late 40's on the same road etc.

Try resetting over just one stretch of road, eliminating stop and start before you get underway on a decent run.

Ah, just thought - aircon was on because of the peeing rain!

Aircon definitely makes a big difference, so maybe a chunk of the difference was because of that and yes, probably driving into a headwind.

Still, a pretty surprising difference!

I was going to ask was it raining when you got your lower mpg figures.

Even with the aircon off, I always find that surface water on the road reduces fuel economy by 5% - 10%. Aircon further reduces economy by 10% - 15%, so that would explain the difference in your figures.

Edited 3 July, 201213 yr by booke23

Interesting!

I can only assume mpg is hit harder than on petrol engines I've owned.

I've only been getting 40 mpg on my commute. Only had he car a week (170 pd Vrs). I'm pleased with that as the m43 I chopped in would do 20 mpg!

How long is your commute?

I drive 8 miles, same route every morning and fuel consumption varies between 35 and 45mpg. The traffic is generally pretty light - average speed around 20mph. The journey is different every morning.

By far the biggest variable is how many times you have to stop and restart - getting 1.5 tons of metal from rest to 30-40 uses lots of fuel. In the first mile or so (while the engine is cold) I go through 4 pedestrian controlled crossings. If I have to stop at every one then 4 times I have to accelerate from rest to 20-30mph with a cold engine - that hammers the consumption. Then there are another 4 sets of lights - hitting 'em on green or red makes a big difference. How many times slowing down/stopping behind someone turning right? Need to slow down for the 3 roundabouts or complete stop? Another couple of right turns - full stop or just slow down?

I assume that over the couple of days you got these figures that the other big hitters (tyre pressures, car load, car service state, weather) were reasonably constant.

But, trying very hard to be diplomatic, there is one more big hitter - and that is the driver. Of the 2nd trip you said "...and was really trying hard to get the best mpg possible..." So you were driving differently on the 2 mornings. Maybe, just maybe, the things you were doing to get the best mpg possible were the wrong things.

changing up through the gears early doesnt always mean you will be driving economically,the load on the engine may increase if you are in the wrong gear as you have to put your foot down a bit more to get the car to respond