Official vs real fuel economy

[weasley]

Q: Why can't I get anywhere near the official fuel economy results for my car?

A: Hmmm.... good question.
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Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE

[daemonoid]

As interesting as it is it does mean that (so long as all manufacturers try the same tricks) we get a useful comparison if not a decent absolute value. Ie a car that scores well in the tests may not achieve the real world performance it suggests, but it will still be better than a car that did more poorly.

I've always taken them as a guide because I know I won't be hypermileing like the testers will.
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@thomasgarrard | www.straitjkt.com | www.racingseven.com

[weasley]

You say that, but it would depend on which factors a specific OEM decided to bend during testing. You can only compare results if you're sure they have been massaged in the same way. Yes, they will all be looking for the best result, but the report suggests that not all cheats are deployed all the time or to their full extent.

Besides, if these were arbitrary relative ratings (rather than practical absolute measures) then why bother with "miles per gallon"? Why not a unitless rating number?
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Yamaha XJ600 | Yamaha YZF600R Thundercat | KTM 990 SMT | BMW F900XR TE

[smegballs]

As long as I can remember, my old man religiously writes down his fuel data every time he visits a petrol station. He has this little blank table print out, and records the total mileage, mileage since last filled up, date, amount of fuel and how much he's paid.

Whacks it into excel later and makes a graph of his fuel consumption...

[Kickstart]

Hi

One reason that automatics come out OK is that the gear change points come down to how the car maker has programmed it (which can be tailored to the test), rather than for a manual when it is rather more down to the test system

Add to which there are the cars which have spoilers that pop up at speed. And tend to pop up at just over the speed for the tests.

All the best

Keith
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[haroman666]

I thought it was just common expectation that a vehicle production company would state a performance figure that would never reeeally be achieved.

It's all marketing.
Nobody should expect any product to meet the claimed performance figures quoted by the OEM.

This was on the news not long ago. In fact the news report came out the day after I'd had a lecture on it.

https://www.bbc.co.uk/news/business-21759258
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The mistresses: 2000 Honda CBR600f, 2000 Honda VTR1000

[BakesBeans]

I blame the Euro emission tests - my old 1.9 PD130 engine got 47mpg without even trying >50mpg if you try.

My newer 2.0 common rail diesel gets 44mpg - and I can't get above it at all - yet should do far better.

I always reset my trip computer when I fill it, and I expect 500miles before the fuel light comes on - I don't always manage that.

Edit: If you want real fuel economy figures, check this website: https://www.spritmonitor.de/ It's for Germany (mainly) but gives true results (and quite alot of people use it).
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Current: Kawasaki ZX636
Previous Bike: Honda CBR600F ABS, Yamaha XJ6 F Diversion ABS, Honda VFR400 NC30

[Rogerborg]

I read about this years ago, from a German university. They reckoned that turbodiesels are particularly bad for it, as the ECU detects that it's under test and dials down the boost. Their conclusion was that real world CO2 emissions haven't dropped in decades.
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[Polarbear]