MPG at 80-85

[Andy B]

Apologies for a second MPG thread.

We do mainly long-distance driving in our gti, and on French and german roads (mais oui!  ) and we get about 30-32 mpg from our Mk5 edition 30.

The fuel figures for new cars aren't very helpful to us, because the european cycle simulates mixed driving, which tends to result in higher figures than when cruising on long distance runs.

Does anyone have a good idea about what a GTD would do over a long journey at such speeds - either Mk6 or Mk7?

I need to rule out (or in!) the GTD. If the efficiency at such speeds is very different, then I won't be able to ignore it.

Danke sehr.

[monkeyhanger]

My dad maintained 85mph from Newcastle to Southampton in his new GTD (about 20 miles on it before the journey, so tight as a drum) and it did 45mpg. Its a DSG and he had the Aircon on at 17C all the way. Go manual in same circumstances and it would have probably done 50mpg, add 5mpg for a run in version and I reckon you'd be looking at 55mpg, a few more without the aircon.

My 170 TDI scirocco manual can do 58-60mpg at a maintained 80mph on a long run in the summer and it doesn't have any eco tech (official combined is 53.3).

[DougL]

80 mph Autoroute/Autobahn kills the mpg. I'd reckon you'd be lucky to see 45mpg. On my 1.6tdi bluemotion, the figure dips into the high 40s. On a long A road run, it gets 55 - 60 mpg.

[Bill_the_Bear]

Isn't the peak efficiency normally 54mph?  The higher you go above this the less mpg you get.

[DougL]

56

[Jimble]

80-85 on your own private road?

[DougL]

80-85 on your own private road?

OP stated French or German roads.... 

[monkeyhanger]

80 mph Autoroute/Autobahn kills the mpg. I'd reckon you'd be lucky to see 45mpg. On my 1.6tdi bluemotion, the figure dips into the high 40s. On a long A road run, it gets 55 - 60 mpg.

To be fair, the 1.6TDI is probably less efficient than a GTD at that speed - the GTD is hardly breaking a sweat, you will be driving the 1.6TDI a lot harder to do the same, that will always affect the mpg even on the most efficient engine.

[DougL]

Agree to a point but the main factor at these sort of speeds is drag. I just did two 400 mile days from Barcelona to St Malo (on a scooter) and the motorway riding dropped the mileage per tank (at 80mph) from 160 to 120.

[dubber36]

On the way to Inters last year in the 140, we were running late so I was pushing on for around 60 miles on the motorway. For the whole journey it averaged a smidge over 50mpg, so at a guess it was doing 45mpg on the motorway.