Real world mpg vs official mpg
Discussion
Hello.
This forum is riddled with people complaining about the unachievable official mpg figures for cars, about what a con it all is, and about how when you drive a GT86 at 6000-7000rpm it only does 26mpg.
Part of the problem is how unrealistic the NEDC test is. The other part of the problem is how the drivers aren’t trying to drive economically.
I get the impression that people don’t understand the NEDC. So to illustrate how different the NEDC is to your morning commute I’ve put in brackets the 0-60 time you’d have to do to match the various acceleration phases required in the test:
0-15 kph in 4 seconds (equivalent to a 0-60mph in 25.7 seconds)
0-32 kph in 12 seconds (equivalent to a 0-60mph in 36.2 seconds)
0-50 kph in 26 seconds (equivalent to a 0-60mph in 50.2 seconds)
0-70 kph in 41 seconds (equivalent to a 0-60mph in 56.6 seconds)
50-70 kph in 13 seconds (equivalent to a 0-60mph in 62.8 seconds)
70-100 kph in 35 seconds (equivalent to a 0-60mph in 112.7 seconds)
100-120 kph in 20 seconds (equivalent to a 0-60mph in 96.6 seconds)
If you habitually did 0-60 in 112.7 seconds you’d get bored. You’d hold up traffic. But it’s not that uncommon to get stuck behind cars (or trucks) which accelerate at this rate.
If you habitually did 0-60 in 25.7 seconds you’ll find yourself held up a lot, and often overtaking other traffic (I know, because I owned a car that took 29 seconds to hit 60).
If you habitually do 0-60 in less time than that you will find the official mpg impossible to achieve.
This is not the fault of the manufacturer (they don’t choose the NEDC test, and they don’t drive your car).
This is not the fault of the NEDC (because the test parameters are published for free, and they don’t drive your car).
This is the fault of the driver.
You can have performance or economy, but not both at the same time, and the problem is the huge difference between the expectations of the average forum user of how much performance you can use without affecting mpg and the performance actually used to achieve the published economy.
We could push for a more difficult test, a test requiring higher performance. Or we could learn to drive economically. What we can’t do it blame the cars or the manufacturers for not being magic – if you demand to match the published mpg and still use full throttle then expect to be sold a car that can only do 0-60 in 112.7seconds.
This forum is riddled with people complaining about the unachievable official mpg figures for cars, about what a con it all is, and about how when you drive a GT86 at 6000-7000rpm it only does 26mpg.
Part of the problem is how unrealistic the NEDC test is. The other part of the problem is how the drivers aren’t trying to drive economically.
I get the impression that people don’t understand the NEDC. So to illustrate how different the NEDC is to your morning commute I’ve put in brackets the 0-60 time you’d have to do to match the various acceleration phases required in the test:
0-15 kph in 4 seconds (equivalent to a 0-60mph in 25.7 seconds)
0-32 kph in 12 seconds (equivalent to a 0-60mph in 36.2 seconds)
0-50 kph in 26 seconds (equivalent to a 0-60mph in 50.2 seconds)
0-70 kph in 41 seconds (equivalent to a 0-60mph in 56.6 seconds)
50-70 kph in 13 seconds (equivalent to a 0-60mph in 62.8 seconds)
70-100 kph in 35 seconds (equivalent to a 0-60mph in 112.7 seconds)
100-120 kph in 20 seconds (equivalent to a 0-60mph in 96.6 seconds)
If you habitually did 0-60 in 112.7 seconds you’d get bored. You’d hold up traffic. But it’s not that uncommon to get stuck behind cars (or trucks) which accelerate at this rate.
If you habitually did 0-60 in 25.7 seconds you’ll find yourself held up a lot, and often overtaking other traffic (I know, because I owned a car that took 29 seconds to hit 60).
If you habitually do 0-60 in less time than that you will find the official mpg impossible to achieve.
This is not the fault of the manufacturer (they don’t choose the NEDC test, and they don’t drive your car).
This is not the fault of the NEDC (because the test parameters are published for free, and they don’t drive your car).
This is the fault of the driver.
You can have performance or economy, but not both at the same time, and the problem is the huge difference between the expectations of the average forum user of how much performance you can use without affecting mpg and the performance actually used to achieve the published economy.
We could push for a more difficult test, a test requiring higher performance. Or we could learn to drive economically. What we can’t do it blame the cars or the manufacturers for not being magic – if you demand to match the published mpg and still use full throttle then expect to be sold a car that can only do 0-60 in 112.7seconds.
I actually set up a website a long time ago to deal with this, called http://www.actualmpg.com/
Sadly I never got around to really finishing the idea, and without a marketing budget it was always going to be tricky to get it off the ground so it lays there doing nothing
Sadly I never got around to really finishing the idea, and without a marketing budget it was always going to be tricky to get it off the ground so it lays there doing nothing
This is interesting:
http://cars.uk.msn.com/features/green-motoring/top...
They managed to beat the official figures by some margin on some of those cars.
I'm guessing their route was more country than town, but still.
http://cars.uk.msn.com/features/green-motoring/top...
They managed to beat the official figures by some margin on some of those cars.
I'm guessing their route was more country than town, but still.
kambites said:
That doesn't help much without knowing how you drive - if only 30% of your driving is "urban" you damned well should beat the official figures.
You absolutely right, how you drive will have an impact on your result. My commute is 9 miles each way of fairly free flowing DC with very little stop/start - If I do 18*5*52 for miles per day by working days by weeks of the year that gives you 4680 miles.
I annually do just under 8k per year and have done since I have owned the car the past 5 years.
The remaining milege is spent traveling door to door going to the gym, visiting friends, family, GF so alot of 30/40 mph journeys.
kambites said:
This is interesting:
http://cars.uk.msn.com/features/green-motoring/top...
They managed to beat the official figures by some margin on some of those cars.
I'm guessing their route was more country than town, but still.
108.8 mpg on the Fiesta http://cars.uk.msn.com/features/green-motoring/top...
They managed to beat the official figures by some margin on some of those cars.
I'm guessing their route was more country than town, but still.
That must have been a very boring drive 
Very impressive though.Gassing Station | General Gassing | Top of Page | What's New | My Stuff