MK7 GTD - Real Life MPG

[corgi]

You should not be surprised that fuel economy suffers as speed increases - once the speed gets to a point where aerodynamics are a factor. The air resistance increases in proportion to the square of the increase in speed... Therefore, as your average speed becomes greater you should see an increasing decline in fuel consumption.

[monkeyhanger]

You should not be surprised that fuel economy suffers as speed increases - once the speed gets to a point where aerodynamics are a factor. The air resistance increases in proportion to the square of the increase in speed... Therefore, as your average speed becomes greater you should see an increasing decline in fuel consumption.

I’m not surprised that economy suffers as speed increases (well aware that air appears thicker due to increased wind resistance as the car speeds up – the main reason that a car with twice as much BHP is nowhere near twice as fast), I’m surprised at how much it affects the GTD compared to previous VWs to go a modest 10mph faster (80mph vs 70mph). For a car that is supposedly 20% better on fuel economy than the previous generation, realistic expectations are that a MK7 GTD should be as fuel efficient straight out of the box as a run in MK6 GTD, and then you should see gains as the MK7 runs in that justified the “20% better mpg” tag. For the MK7 GTD to be 30% away from book combined figures for most users right now, compared to 5-10% away from book combined being easily achievable in MK6 GTD/Scirocco 170TDI, that is the issue. Can anyone realistically expect to see 20% running in gains on their new GTD to bring them routinely within 10% of book combined after 5k-10k miles? I very much doubt it. Seems plenty of people here are having to do very long journeys to crack 50mpg in their new GTD. An 80mph cruise on a long journey (100+ miles) in my 170TDI Scirocco would have yielded an easy 55mpg in the worst of weather.

[Misterp]

MH this is exactly my point.  You can understand being 10% off the urban and combined cycle figures but 30% or more that just isn't right. Factor in the gains after running in I honestly can't envisage a 20% increase after running in.

[corgi]

I refer you to the link I posted yesterday and my comment that as the official test is not representative, if you expect 25% worse fuel consumption than the official figures, then you will not be disappointed.

In the end, I suspect that modern ECUs are so sophisticated that they may even be able to recognise that a test is being performed and behave accordingly...

[monkeyhanger]

I refer you to the link I posted yesterday and my comment that as the official test is not representative, if you expect 25% worse fuel consumption than the official figures, then you will not be disappointed.

In the end, I suspect that modern ECUs are so sophisticated that they may even be able to recognise that a test is being performed and behave accordingly...

It’s not representative now, but it was up until recently by my past experiences of not having to try too hard to get close to official combined figures on a shortish journey (<20 miles) and surpassing it on a longer one.

Do VW officially state that it isn’t representative of real life situations anywhere? Haven’t seen anything to that effect myself unless you take the use of “up to”.

What I have seen quite prominently on a Mazda TV advert for the Mazda 6 is that they declare that their official combined cycle results may not be representative of real driving results and are to be used for comparison with other car manufacturers only. It would seem then that Mazda are quite honest and by association with their non-real world test figures, the same can be expected of the other car manufacturers also (for it to be a fair comparison). I do think it is completely wrong to just accept 75% of claimed combined figures as “doing ok” when they have sold the MK7 as being 20% better than the previous generation on fuel usage.

Although I do bang on about mpg quite a bit, it isn’t the only reason I bought a GTD. If they’d said here it is, you might get 50mpg if you’re lucky, but aim for 45mpg I’d have probably still bought one, but some others maybe have bought for the non-existent fuel savings.

With the weight saving*, start-stop, brake regen etc tech not present on my last car I think it’s fair to assume you would see better mpg on the new one than the last gen MK6 GTD or Scirocco 170TDI.

* Weight saving “up to 100Kg” – another stretch of the truth. Pretty much a universal 27Kg saving on any MK7 Golf that retained the multilink rear suspension (>120PS).

[corgi]

Do VW officially state that it isn’t representative of real life situations anywhere? Haven’t seen anything to that effect myself unless you take the use of “up to”.

What I have seen quite prominently on a Mazda TV advert for the Mazda 6 is that they declare that their official combined cycle results may not be representative of real driving results and are to be used for comparison with other car manufacturers only. It would seem then that Mazda are quite honest and by association with their non-real world test figures, the same can be expected of the other car manufacturers also (for it to be a fair comparison). I do think it is completely wrong to just accept 75% of claimed combined figures as “doing ok” when they have sold the MK7 as being 20% better than the previous generation on fuel usage.

I'm not saying that this is the way it should be, just the way it is...

It is not all cars either - being cynical - cars that suffer this problem most are those in the competitive mid-range hatch market. "Honest John" shows that some cars - for example Jag, Porsche achieve the same or better than their official figures and diesel powered cars seem to be worse.

My girlfriend, a few weeks ago, took delivery of a new 120d M-Sport which should officially do 65.7mpg on the combined cycle, the trip computer, last I looked, was reporting 48.5... more than 25% off... Now, she is not the most economical driver but I would have expected better...

The point here is that the test is not representative of the driving she does... the extra-urban test only briefly reaches a peak speed of 75mph and has an average speed of 40 iirc - she, on the other-hand, has a commute of about an hour, often in congestion but when it is clear she will settle into a cruise higher than the peak speed of the test...

With my likely driving in my GTD when it arrives and is run-in, I would expect to see high-forties to low-fifties as mpg... Anyone expecting to see close to the combined figure for the GTD (67.3) would need to drive as per the tests... and even then I reckon they would only be within 5% because there are so many other factors at play that the test doesn't really address...

The previous tests were not seen as representative (urban/56/75) because they did not represent normal driving but neither do the current tests and having read what is proposed I doubt the upcoming ones will either...

[Misterp]

Vw were recently given a slap on the wrist for the figures they quote and the manner in which they advertise it they have been told to state as per Mazda. That being said you would be silly hoping for the quoted figure but 30% discrepancy. That's taking it too far.

[corgi]

Vw were recently given a slap on the wrist for the figures they quote and the manner in which they advertise it they have been told to state as per Mazda. That being said you would be silly hoping for the quoted figure but 30% discrepancy. That's taking it too far.

From the article I posted yesterday:


A recent study  by The International Council on Clean Transportation (ICCT) showed that, on average, ‘real world’ fuel consumption for new cars was 21% worse than the figure quoted by the vehicle manufacturer.

No one standard test can accurately reflect the diversity of driving style, road, traffic and weather conditions, and drivers have probably always expected some variation compared to official figures, but in some cases the gap is now so wide that drivers are accusing manufacturers of misleading claims and even suggesting legal action.

and more

Research by TNO and Travel Card in the Netherlands ... showed that cars use over 35% more fuel than manufacturers claim.

And the AA's opinion (not mine)

If you assume that the car will be capable of a fuel economy 25% less (worse) than the official combined figure quoted by the manufacturer you shouldn’t be disappointed, and may be pleasantly surprised.

As I said earlier, I'm not saying it should be like this but it is. In the end the official tests are to blame, the manufacturers optimise their cars for those (when they feel it is important to do so)... make the tests more representative and the discrepancy will be less...

[AMarsh]

I've been averaging around 45mpg, but got 55mpg on an half hour run tonight.  It is really cold and car hasn't been driven for a few days, so it took forever for the oil temperature to get to a decent level. I'm sure if the car was warm, I would have got close to 60mpg. 

Not sure if it is in my head but the car felt a lot looser tonight and that bit faster.  Just went past 750 miles.

Be delighted if i get anywhere near 50mpg. 

[KyleB]

I;ve been getting between 45-60mpg on my runs. This is on the a182 (40/50/60mph) road and the a19 (70/80mph) road. Weirdly I seem to get better MPG in Sport mode, which I can only put down to needing to press less hard on the throttle?

Disappointed to not get into the 50s more with the MPG but it is no worse than my last car (1.4 Ibiza) with a lot more power on tap too.