This ought to be re-emphasized: modern fuel economy numbers listed on the sticker are not the same as those from the 1970s. The underlying tests are the same, but the reported sticker number is adjusted downward to reflect a more typical driver. This pdf details the rationale behind the current calculations.
Many vehicles use the MPG-based approach given on page 103 of that document. Using those formulas, the 1977 Mazda that tested out at 46 highway / 35 city would be stickered today at 33 highway / 27 city.
Oh, some of them had tons of power. It just wasn’t applied as efficiently as today. I still love the sound of muscle cars. But I know that a modern Audi is also a wonderful thing, even though it is quieter. It turns corners better too.
Sort of. After 2008, the *methodology *for calculating estimated city and highway mileage changed, nominally to include the effects of additional cycles. Test procedures for the city and highway test cycles have not changed. Moreover, for many vehicles, rather than run the additional cycles, the effects of the additional cycles are derived. That means the city/highway sticker fuel economy numbers are calculated using *only *the city and highway tests, using the formula I linked to above. These calculations are different than those used pre-2008, but still adjust the dyno test values downward.
So it’s still possible to do a comparison between 2012 fuel economy sticker numbers and 1977 fuel economy sticker numbers, so long as you remember to adjust the 1977 numbers correctly. For a feel of the difference, this page has data files containing both unadjusted test numbers (which was what would be on the sticker in 1977) and the resulting sticker number for all vehicles.
*As a means of reflecting real world fuel economy more accurately, the EPA *adds three new tests[41] ** that will combine with the current city and highway cycles to determine fuel economy of new vehicles, beginning with the 2008 model year.[42] A high speed/quick acceleration loops lasts 10minutes, covers 8 miles (13km), averages 48mph (77km/h) and reaches a top speed of 80mph (130km/h). Four stops are included, and brisk acceleration maximizes at a rate of 8.46mph (13.62km/h) per second. The engine begins warm and air conditioning is not used. Ambient temperature varies between 68 °F (20°C) to 86 °F (30°C). The air conditioning test raises ambient temperatures to 95 °F (35°C), and the vehicle’s climate control system is put to use. Lasting 9.9minutes, the 3.6-mile (5.8km) loop averages 22mph (35km/h) and maximizes at a rate of 54.8mph (88.2km/h). Five stops are included, idling occurs 19 percent of the time and acceleration of 5.1mph/sec is achieved. Engine temperatures begin warm. Lastly, a cold temperature cycle uses the same parameters as the current city loop, except that ambient temperature is set to 20 °F (−7°C)
If that was in response to me, then you might want to explain why the section you bolded is different from “include the effects of additional cycles.” Or are you agreeing with me?
In other words, the same “city” and “highway” tests are run today as were run 10 or 20 years ago: there are no changes to the test procedures for those cycles. The change is is the *calculation *of the reported fuel economy numbers, which now nominally include the effects of *additional *cycles.
