Consumer Reports Finds How Fuel Economy And Performance Drops When VW Diesels Stop Cheating

Jalopnik ^ | 10/09/15 3:17pm | David Tracy

[Cowman]

So Consumer Reports decided to put a 2015 Volkswagen Jetta TDI and a 2011 Jetta Sportwagen TDI to the test. To activate the car’s cheat mode, they pumped the accelerator pedal 5 times while the ignition was in the “on position” but the engine was off. To avoid being “kicked out” of the cheat mode when the car noticed the rear, undriven wheels spinning, CR simply unplugged the rear wheel speed sensors. Simple as that. Cheat mode activated.

They ran their standard Consumer Reports drive cycle. This involved a city traffic simulation on the track and a 65 MPH highway run on the local highway.

Fuel economy numbers were determined by taking fuel readings from a flow meter and averaging MPG numbers in both directions to account for grades and wind speed, and tests were run several times with different drivers to guarantee consistency.

Here are the numbers: On the 2011 Jetta TDI, 0-60 times increased from 9.9 to 10.5 seconds but the 2015 Jetta’s acceleration numbers were unaltered.

But the biggest changes occurred in fuel economy. Especially on the highway where the 2015 Jetta’s MPGs dropped from 53 to 50 and the 2011 Sportwagen’s plummeted from 50 to 46 MPG.

That’s a pretty significant change for both cars, and considering how many different cycles Consumer Reports ran and how many checks they have for verifying their figures, these numbers definitely seem credible.

But Volkswagen’s fix probably won’t involve always running with the “cheat mode” engaged— there may be durability concerns. We don’t know yet. So TDI owners— we’re not saying your car will become lethargic and lose about 10% in fuel economy. We really won’t know until VW decides how they’ll fix their cars.

[killermosquito]

If a car gets better gas mileage and is more efficient it is going to use less fuel overy the life of the vehicle. Which means less pollution. How many more gallons of fuel will be burned because of government regulations?

[Cowman]

How many more gallons of fuel will be burned because of government regulations?

And consider this; how can more damage be done to the environment by the car that is burning less fuel?

In my state vehicles made prior to 1996 are exempt from emissions testing but all 1996 and later vehicles are subject to the full range of tests and are required to meet the same levels as a new Prius. My question is what is the difference between the exempt 1995 vehicle and the non exempt 1996 vehicle when in most cases the parts are completely interchangeable between them.

The whole scheme of emissions testing came about from the Clean Air act of the Seventies -- Another product of the malaise era -- And was never really about clean air but about control of motorists (anybody remember the intimate familiarity you had with the last number on your license plate?)

It is my contention that the testing is completely arbitrary and unnecessary ant is simply another means the State has of getting into the wallets of motorists.