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Official MPG Figures Unrealistic, Says UK Auto Magazine
Taco Cowboy (5327) writes "Research carried out by UK consumer magazine What Car? which concluded that official manufacturers' MPG figures are unrealistic. Based on the research, new car buyers in the UK who trust official, government-sanctioned fuel economy figures will pay an average of £1,000 (€1,216) more than they expect on fuel over a three-year period. Since launching True MPG two years ago, What Car? has tested almost 400 cars in real-world conditions, using cutting-edge test equipment and achieving economy figures that are on average 19% lower than the government figures."
Under-inflated tires, lousy fuel, ignored maintenance, rapid acceleration, more than one occupant / actual cargo, stop-and-go traffic, air pollution, air pressure variation, air temperature variation, elevation variation...
And these are just a few of the things that would cause your "official" MPG figures to deviate from observations.
Your concern might be less of a troll if you knew that the standard metric measure for fuel economy isn't km/l, but rather l / 100km.
Isn't the more important thing that the all the cars figures are comparable.
We pretty much already knew that the MPG we saw on the sticker was higher than the MPG we would actually be getting. Hence the phrase "your mileage may vary."
But we also know that the sticker MPG numbers are good for comparing among similar cars, and that's mostly how we use the sticker MPGs. Kudos and thanks to 'What Car?' for calculating the 19% offset figure. I wonder if they could tell us how the offset varies among different types of cars. Maybe SUVs vs econoboxes vs sports cars have somewhat different offsets.
BTW, I would bet that different driving styles, lead foot vs hypermiling, makes a bigger differnece than the 19% calculated by 'What Car?'
--- Often in error; never in doubt!
We all knew from previous reports, even in the US, that car manufactures will cheat and use "perfect conditions" and also gut the car of anything they can get rid of to decrease the weight and increase the MPG. Why are governments not requiring actual roadway numbers with an actual car as it comes out of the lot? Because lobbyists from the car manufacturers prevented it; Ether way I've always looked at the MPG and subtracted 20% from it.
before making *any* judgement you *need* to watch the program on 5th gear which covers exactly this question in some detail. basically the test was designed originally for people driving sensibly, and it was designed i think well over 20 possibly even 30 years ago. so it has a very *very* gentle acceleration and deceleration curve. gentle acceleration because that is not only fuel-efficient but also the cars of that time simply could not accelerate that much, and gentle braking because again that is more fuel-efficient but also because if you had drum brakes they would overheat.
people no longer drive sensibly: they are more aggressive with other drivers (not keeping a safe distance), they put their foot down hard on the accelerator and they put their foot down hard on the brake. also as the cars are more reliable they tend to not maintain them properly: until i watched another program on 5th gear about how badly old oil affects fuel economy and the lifetime of the engine i had absolutely no intention of changing oil regularly in the decade-year-old cars i buy.
so, in effect, people should stop complaining and start driving in more fuel-efficient ways... *regardless* of how aggressive the person behind them gets when they set off from the lights at the same acceleration rate as a 40 tonne cargo lorry. that's the other person's problem.
.... arn't the best solution. If they're so underpowered or peaky - like a lot of the new generation coming along - then people will tend to drive with their foot flat to the floor a lot mroe often which hammers fuel consumption and doesn't do the mechanicals any favours. Whereas with a bigger engine this is less of the case and you can get equivalent mpg except with a less stressed engine that isn't going to blow a seal after 75K miles because of components being worked to their limit to make up for the idiotically small capacity.
Of course left to their own devices no manufacturer would be dumb enough to put a 1.0L engine in a 1.5 ton car but EU regs now require silly emissions targets being met in these unrealistics tests so the manufacturers have no choice.
Your concern might be less of a troll if you knew that the standard metric measure for fuel economy isn't km/l, but rather l / 100km.
While km/L is less common, it certainly does appear as an alternative measure in many countries, particularly to allow people to compare it to mpg metrics (as the GP was suggesting here, since the title of this story is about "MPG"). You are correct that in many countries, L/100km is standard.
Before we get the standard debate about this crap that comes up every time this topic comes around, let me just point out that the reciprocal relationship between these two measurements doesn't mean one is "more correct" than the other. Rather, both will give intuitive results for different questions or given different constraints.
For example, if you're buying a car primarily for commuting, gas consumption per distance (e.g., L/100km) will give you an intuitive sense of your fuel cost, since your daily distance is relatively fixed. If your L/100km doubles, your fuel cost for fixed commutes will double.
On the other hand, if you're buying a car primarily for occasional longer trips and not using it for regular commuting, distance per gas unit (e.g., mpg or km/L) will give you a more intuitive sense of how far you'll be able to travel with the same gas budget. People buying a car only for occasional trips probably are more likely to care about how far they can go with a given amount of fuel rather than how the fuel cost will vary for a fixed distance. If your MPG doubles, you can go twice as far with the same amount of fuel.
Different metrics are useful for different things. These two have a very clear relationship, but when non-math-literate people are comparing the raw numbers, one can be better than another in making decisions depending on the situation.
Probably also driving too fast... European emission standards require testing at 90km/h, while the max speed in most EU countries is 120 or 130km/h
I'm in the U.S. and my car is rated 22mph city 29 mph highway. The city rating is dead on. The highway rating is off, I actually get 34 mph rather than the stated 29. My typical highway is designated 65 mph and when traffic is light it is practical to do 75 mph. At 75 mph I get 34. The rating of 29 may be based on obsolete 1970's 55 mph standards.
Maybe 55 was optimal with 1970's auto technology but it doesn't seem so today, at least for me. And of course YMMV is quite appropriate here.