The NEDC is supposed to represent the typical usage of a car in Europe.
March 14, 2013 11:34 AM   Subscribe

Mind the Gap! Why official car fuel economy figures don’t match up to reality. This report provides new evidence and understanding on why there is a growing gap between the official fuel consumption and CO2 emissions of new passenger cars and vans and that which is achieved by the same vehicles on the road. It demonstrates that the current (NEDC) test is outdated and unrepresentative of real-world driving and current vehicles, and that lax testing procedures are allowing car-makers to manipulate the official tests to produce unrealistically low results

When the road load test procedures were drafted 30 years ago, no-one expected carmakers to adjust the brakes, pump up the tyres, and tape up all the cracks around the doors and windows to reduce the air and rolling resistance. These practices are now commonplace, with testing facilities being paid to optimise the results of the tests. There is no evidence that carmakers are breaking any formal rules - but they don’t need to - the current test procedures are so lax there is ample opportunity to massage the test results.
posted by three blind mice (10 comments total) 4 users marked this as a favorite
Just in case you are wondering, this is how it's done in the US. Much more controlled and regulated, but does tend to miss some real-world factors.

The US test purportedly errs on the high side for hybrids, and on the (very) low side for diesels.
posted by schmod at 12:04 PM on March 14, 2013

They revised the US system for 2008 and later, too, as cars were testing with better fuel economy than people were getting in the real world. The 2008 and later ratings seem much more accurate.
posted by tylerkaraszewski at 1:07 PM on March 14, 2013

You've be naive to imagine car manufacturers haven't been overpressuring their tyres and doing other mechanical tricks since forever. What's different now is the new technology in the car that consumes a lot of power - which can be turned off for the test. I drive a lot of different cars to and fro work on the exact same route (50km, 25% of it highway and 75% built up) and one of the things I really pay attention to is the fuel economy.

It's not a coincidence that the car with the best results versus the official number was a low spec manual hatchback with nearly no electronic features on it and a crappy air conditioning unit. In fact, in the 5 month average I was driving it, I got better than advertised fuel economy.

And the car with the worst results versus the official number had the most number of fancy features: an incredibly strong air conditioning unit that would more than match Melbourne's crazy 43 degree C weather in minutes, built in sat nav, full phone integration, automatic parking, and a crapload of other features. You'd turn on the air conditioning on full blast and you'd see the fuel use go up by 0.7 litres per hour, while other cars only went up by 0.2 or 0.3.

Yes, even turning on the headlamps causes fuel consumption to go up noticably. Say 1% to 2% more fuel consumed for a night drive versus a day drive.
posted by xdvesper at 4:19 PM on March 14, 2013 [1 favorite]

Honda has definitely been paying for this sort of misrepresentation re: the gas mileage of its early models of hybrid cars (and the hybrid battery life, and the life of certain other parts, and the odometer accuracy...) in a series of settlements and recalls. I love their cars, but unfortunately, I've been paying a lot more for gas and repairs on my hybrid than I would like.
posted by limeonaire at 5:01 PM on March 14, 2013

My dad still misses his 1978 Datsun 210. 40MPG in the real world- AND it had air conditioning.
posted by dunkadunc at 8:15 PM on March 14, 2013

schmod:Just in case you are wondering, this is how it's done in the US.
Great link, but I think it's worth pointing out something they spell out right up front:
Manufacturers test their own vehicles—usually pre-production prototypes—and report the results to EPA. EPA reviews the results and confirms about 10-15 percent of them through their own tests...
In other words, the EPA probably did not measure anything at all to arrive at a fuel economy figure used to advertise any given US-market car.

I wonder how much ratings like these are really still relevant in the internet era. It's usually easy to find better, more relevant real-world figures for most models.
posted by Western Infidels at 10:00 PM on March 14, 2013

Fuel economy testing is also responsible for the current race to fit the most gears possible into a gearbox. The new Range Rove Evoque will get a 9-speed automatic.
posted by Harald74 at 12:39 AM on March 15, 2013

Weird. I've generally found the latest revised EPA mileage ratings to be fairly accurate and even conservative (by which I mean with careful driving I can generally beat them). But then my cars are all at least 10 years old and generally not laden with ridiculous features that distract from the essence of driving. It's actually essentially impossible to buy a new car with the level of standard features as my 92 Storm. Even base models come with power windows, mirrors, locks, often A/C and power seats. And then the only useful gas economy feature, cruise control, is only available with top level trim packages bundled with 12 speaker stereos, Sat Nav and Heated seats.

I wonder how the move to even commuter cars having 16 and 17" tires is effecting fuel economy. Those huge rims weigh a lot more than the 13-14" rims small cars used to have.
posted by Mitheral at 6:30 PM on March 16, 2013

Power windows aren't taking away from your fuel economy. It usually costs more to build the tooling and a second production line for cars without power windows than it does to just put the motors into every car that comes out of the factory.

However, you can get a Nissan Versa without power windows/mirrors/locks/seats, and the cruise control option only costs a bit more (and comes bundled with a more efficient transmission). It's one of the cheapest new cars that you can buy in the US, and actually not at all a bad car to drive.

The assholes at Nissan will still stick you with Air Conditioning though. Toyota, Honda, and Hyundai all used to allow you to buy a "base model" of some of their cheaper cars. A/C was still listed as an optional feature on the Honda Civic when I was shopping around for cars in 2009. I also test-drove a Toyota Yaris that looked like it had passed through a chop shop -- no radio, no lid on the glovebox, and the only things on the dashboard were the speedometer and a tiny digital gas gauge (and it wasn't even all that cheap!).

The funny thing is that these (seemingly important) missing features cost virtually nothing to add in. The "sane person's base model" was usually just a tiny bit more expensive.

Engine and transmission technology has improved by leaps and bounds over the past decade, and most of those improvements have trickled down into even the lowest-end models on the market. A new car is going to be cleaner and more efficient than your 1992 WhateverItIs, no matter how many extra features it has bolted onto it. You're also going to be a lot less likely to die if you crash the thing.
posted by schmod at 1:58 PM on March 19, 2013

Power windows generally weigh more than manual winders. Sure it's only a pound or two but it's still a factor.

I totally agree on newer cars being better in pretty well every metric; that's why I was shopping for a newer car. I just object to the extent that the standard feature list on many cars has bloated adding weigh and complexity. I'm not looking to return to the days when heaters were optional but it sure would be nice to be able to buy a basic car.

Admittedly my search was significantly restricted because I wanted a manual transmission two door coupe or hatchback; there may be some stripper sedans out there.
posted by Mitheral at 5:43 PM on March 19, 2013

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