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Model specific boards => Golf mk7 => Topic started by: Andy B on 05 July 2013, 20:05

Title: MPG at 80-85
Post by: Andy B on 05 July 2013, 20:05
Apologies for a second MPG thread.

We do mainly long-distance driving in our gti, and on French and german roads (mais oui!  :shocked: ) 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.
Title: Re: MPG at 80-85
Post by: monkeyhanger on 05 July 2013, 20:16
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).
Title: Re: MPG at 80-85
Post by: DougL on 05 July 2013, 20:17
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.
Title: Re: MPG at 80-85
Post by: Bill_the_Bear on 05 July 2013, 20:36
Isn't the peak efficiency normally 54mph?  The higher you go above this the less mpg you get.
Title: Re: MPG at 80-85
Post by: DougL on 05 July 2013, 20:53
56
Title: Re: MPG at 80-85
Post by: Jimble on 05 July 2013, 21:03
80-85 on your own private road? :lipsrsealed:
Title: Re: MPG at 80-85
Post by: DougL on 05 July 2013, 21:05
80-85 on your own private road? :lipsrsealed:

OP stated French or German roads....  :wink:
Title: Re: MPG at 80-85
Post by: monkeyhanger on 05 July 2013, 21:35
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.
Title: Re: MPG at 80-85
Post by: DougL on 05 July 2013, 21:41
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.
Title: Re: MPG at 80-85
Post by: dubber36 on 05 July 2013, 21:55
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.
Title: Re: MPG at 80-85
Post by: Gordor on 05 July 2013, 22:02
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.


Doesn't the 1.6tdi only have 5 forward gears though? That would make a massive difference on the motorway surely?
Title: Re: MPG at 80-85
Post by: monkeyhanger on 05 July 2013, 22:03
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.

Aye, pushing through the air at 85mph is a lot harder than 60mph, but even so, my dad achieved 45mpg in his new GTD DSG at 85mph on a long journey under the worst of circumstances (aircon working hard, new car not run in, DSG has a greater penalty in fuel as it is geared lower than the manual). I think the OP can easily expect this at a minimum considering my dad's less than efficient cruising speed and the achilles heel of DSG economy (assuming he could be getting a manual).

That 1.6TDI (105PS I assume, not 90PS version which will be working even harder) will be working a lot harder to overcome the drag than the GTD, so a car doing 70% of it's potential output vs a car doing 40% of it's potential output (both probably outputting about 75PS to maintain that speed) will be a lot thirstier even though on paper it is 10% more efficient on the combined cycle.
Title: Re: MPG at 80-85
Post by: mcmaddy on 05 July 2013, 22:04
I've found the sweet spot on all of the diesel vag engines I've had is 82mph
Title: Re: MPG at 80-85
Post by: ajmoir36 on 05 July 2013, 22:06
I have actually found peak mpg at 52mph (mk6 GTD)
Title: Re: MPG at 80-85
Post by: monkeyhanger on 05 July 2013, 22:14
I find the 2.0TDI has the least penalty for mpg at the higher cruising speeds. They are most efficient at 55-60mph, but the trade off above that to 80mph is relatively small. Sounds like the OP does a canny bit of high speed cruising, especially in Europe where he can take advantage of significantly cheaper diesel prices.

You'll be looking to 40mpg on a long trip at 80-85mph in a GTI and 60mpg on a GTD when they're run in (assumed manual transmission). It's up to the OP to decide whether they do the miles to consider the GTD a better buy for them for what they'll be looking to do with it.