Skip to comments.Why car makers lie about fuel consumption (in Europe)
Posted on 04/28/2012 12:06:31 PM PDT by Olog-hai
There are lies, damn lies, statisticsand official EU car fuel consumption figures. I and others have been banging on about this for years; the figures quoted by manufacturers in their ads usually (but, interestingly not always) bears absolutely no relation whatsoever to what happens in the real world.
To get those official figures, new cars are subjected to something called the New European Driving Cycle, a series of short runs on a rolling road where the car is accelerated, put on a short cruise and decelerated under laboratory conditions. All the car makers have to put their cars through the same test, so on this level, there is no trickery involved. The idea is that the EU has created a level playing field upon which the performance of all cars can be judged.
But it is not as simple as that. Because this is where it gets clever, and some trickery DOES creep in. Some years ago, manufacturers realized that to score well on the official tests, they could tune their engines for maximum efficiency on the rolling road cycle. This was particularly the case for small turbocharged diesel or petrol engines and hybrids. For instance, the engine could be set up so that the turbocharger simply does not kick in during the cycle. But take the car out onto a real road and to get the thing to move at all, the turbo will be needed, massively increasing consumption.
(Excerpt) Read more at hanlonblog.dailymail.co.uk ...
Not so much. This road test of the 1962 Impala SS puts the normal range at 10/13 mpg.
...and a 1969 Caprice at 8/11 mpg!!
Fuel was cheap so no-one really cared.
I think this is because they test it with the AC running nowdays. It was one of the gimmicks the government came up with to force cars to get better mileage without changing the official CAFE requirements.
The A/C change had to do purely with Cadillac ,, they had a trigger set in the engine computer back in the 1980’s and early 1990’s that would run the engine just right for emissions testing with the A/C OFF .. the car ran like crap ,, drivability really stunk but it passed the emissions tests ... with the A/C ON the computer ran on a totaly different fuel and ignition map and ran fine but flunked emissions ...
How about filling the tank with fuel, driving it until the fuel gauge indicates it is prudent to refill the tank, then dividing the total distance driven since the last fillup, by the amount of fuel needed to again top off the tank?
Seems like a pretty reliable indication of the mileage potential. In real time and in real conditrons.
Years ago, Mobil held a “Grand Canyon Economy Run”, which provided just such figures on a real driving course, all vehicles in direct competition, following the same road and driving conditions.
Studebaker Champions came up with some pretty impressive numbers. And this was back in the late 1940’s and early 1950’s.
I drive a 2005 Chrysler 300C and get over 30 mpg highway. I was looking at a new 2012 300 and the sicker claimed only 25 mpg. Same engine, same accessories etc.
That’s how it is now. Rather than increase the CAFE requirements(which would make people angry and requires government action) they did the back door method by having the EPA change the parameters of their fuel mileage tests. Cars have more horsepower nowdays and if you use that HP stupidly, your mileage goes down real fast. In other words, your mileage varies more depending on how you drive. That makes it easier for the EPA to get the mileage results they want to get by adjusting the parameters of the test.
Higher power would mean less throttle required to match the acceleration graphs on the test equipment ,, should mean higher mileage ... at least as far as a hemi 300c is concerned as the car is substantially unchanged... I don’t think the test has changed much ,, you should be able to make valid comparisons between current and prior years ... http://www.nhtsa.gov/fuel-economy
Lower powered cars operating at closer to max power are more efficient than high powered cars operating at lower power levels. Stated another way...
a 100 horsepower engine operating at 100% output is more efficient than a 200 horsepower engine operating at 50% output. Both are generating 100 horsepower but the more powerful engine consumes more fuel.
If the turbos on these cars were bypassed to fudge the test in a certain rpm range, owners would immediately notice and complain. Like I said before, the days of turbo lag are long gone. Today there is seemless, smooth power from just above idle to close to redline.
Anyway, there are dozens of car magazines (if anyone reads those anymore) and hundreds of car-specific websites that will tell a prospective owner what milage can be realistically expected.
Everyone knows that the “officially” stated figures were derived from some test under lab conditions and may (will!) vary from the real world. All that those figures are useful for at best (if one really cares at all) is as a relative measure between different cars.
That 25 mpg hwy is actually the same as the sticker in 2005 ,, EPA shows that 2007 and earlier years mileage estimates do not compare directly ,, looks like a calculation change rather than a test change .. http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=20966 click on “view original EPA mileage” about mid page.
The ones I drove got between 12-18 mpg. '69 Catalina/'69 Firebird, etc. Had a '61 Chevy belair with a 235 cu 6 in it and it was lucky to get 20 on the highway. You must have run into some extraordinary full size '60s cars.
I understand about pumping efficiencies, however cars typically cruise at about 10-15% of rated power with huge reserves ... if we were talking about 50% power and 100% power that’s one thing ,, what we have is a car using 6% power to cruise rather than 8% of it’s power ,, CARS ARE NOT AIRPLANES.
In the 60s, the only benefit to getting a smaller engine was the car was cheaper to buy. Smaller engines didn’t cost much less to operate and they wore out much quicker. Most people wanted the biggest engine they could get.
Every engine is different .. what you need to see is a chart/graph of BMEP vs. Fuel Burn to determine the engines most efficient RPM ... with a load equal to whatever “road horsepower” (rolling resistance plus aerodynamic drag) you need for a certain speed.. BMEP alone is useless on a dyno if you are just looking for max horsepower.
Generally speaking, the smaller engine operating at closer to peak output is more efficient. If this weren’t true, hybrid cars would not get better mileage than non-hybrids.
How many forward gears on the Corvair though? If youve got the two-speed automatic, you cant expect high acceleration. Never mind dual overhead cams, multiple valves per cylinder and electronic fuel injection making yet more of a difference, curb weight rounding everything off. Comparison of apples to apples would be more like itthe original Corolla E10 (first year in US was 1968) came with an OHV 60-hp inline four-cylinder, with transmission options of four-speed manual and two-speed automatic. (Cant find performance figures for the automatic though; the stickshift managed a 0-60 in 16.8 seconds and quarter-mile time of 20.0 seconds, and I dont see the two-speed automatic beating that.)
The thread concerned mpg. Today’s vehicles are heavier and faster, but still get better mpg.
Newer mid-size (and even larger) cars do 0-60 in under 7 seconds and get 25+mpg in mixed driving, not to mention handling much better. Mid-’60s muscle cars were barely faster and got half the mpg.
But there was something enjoyable about those big bench seats and lots of elbow room. And there was no beeping and buzzing! Many vehicles today give the feeling of being strapped in a padded bathtub.
The truth is that the figures are only useful for comparison purposes. No set of testing can come even close to a real-world scenario.
Is it where HP/torque cross and BSFC is the lowest or a point where volumetric efficiency has peaked? Yes airplanes engines are different...
Still a vast gap in technology. Also, big block V8s were in their infancy in the mid-60s. Theres going to be a wide gulf between the capabilities of a 24-valve 4OHC V6 multi-port EFI mated to a 6-speed automatic and that of an OHV V8 2BBL mated to a Powerglide 2-speed automatic (even the base-model 2012 Camaro V6 has 325 horses, a number youd be lucky to get with the 327-cid small-block V8 of the mid-60s). The sheet metal on the 60s cars, though, is quite another story. And no, not all new cars are heavier than 60s cars; you wont see too many new cars over the 5,000-lb mark.
Newer mid-size (and even larger) cars do 0-60 in under 7 seconds and get 25+mpg in mixed driving, not to mention handling much better. Mid-60s muscle cars were barely faster and got half the mpg