I think you may wish to consult some actual charts like I did. Gasoline Engine: http://paultan.org/images.paultan.org/uploads/2006/08/a4test_2tfsitorquecurve.j

I think you may wish to consult some actual charts like I did. Gasoline Engine: http://paultan.org/images.paultan.org/uploads/2006/08/a4test_2tfsitorquecurve.jpg http://paultan.org/images.paultan.org/uploads/2006/08/a4test... Diesel Engine: http://g35driver.com/forums/attachments/g35-sedan-v36-2007-08/141825d1312931616-traded-g35-tigtorq1.jpg http://g35driver.com/forums/attachments/g35-sedan-v36-2007-0... > They are only efficient if allowed to pollute! [Citation Needed] Industry mags are predicting the MPGs will meet the EPA Window Sticker and the emissions requirements. http://www.edmunds.com/car-news/how-the-volkswagen-diesel-scandal-will-affect-your-tdis-mpg-rating.html http://www.edmunds.com/car-news/how-the-volkswagen-diesel-sc... https://www.cars.com/articles/vw-diesel-owners-should-get-epa-mileage-after-fix-1420681342830/ https://www.cars.com/articles/vw-diesel-owners-should-get-ep... Wired's informal testing shows less than a 10% decrease in fuel efficiency when tricking the ECU into going into "test" (and therefore NOx-compliant) mode: http://www.wired.com/2015/10/vw-diesel-cheat-mode-mpg-performance/ http://www.wired.com/2015/10/vw-diesel-cheat-mode-mpg-perfor... Of course, the actual results remain to be seen. You might want to check out the tdiclub.com forums, there are some top techs on there that explain what is really going on.