TrueDelta asks readers some pretty standard questions and gives detailed instructions on how to figure out your mpg. Looking through the submission site, the one obvious change Karesh should make is to include a field for type of fuel used to achieve the results. With E10 and E85 (and biodiesel for diesel cars) available in more places and affecting vehicles' performances, factoring this variable into the results would really set TrueDelta apart.
Let's take a look at one TrueDelat example, the resulte for the 150-horsepower 2.5L I5 6-spd shiftable automatic FWD 2006 New Beetle. The EPA pegs this car at 23 city/32 highway. TrueDelta readers say it gets 29 mpg when driven in a flat area, using a medium foot (slightly faster than other cars in traffic) at an average of 60 mph. Right now, those two results are pretty similar, but it feels like we're getting a better idea of the car's performance from TrueDelta. It'll be interesting to see where TrueDelta's numbers go when more people participate.
So far, over 1,000 people have submitted their numbers to TrueDelta's fuel economy survey, so Karesh just these first responses. He knows that the more people participate, the more accurate the ratings will be. If you want to help outdo the EPA, head on over and tell Michael how your car's been driving.