Please consider adding more specific selections for engines. Differences between engine sub-types are very relevant. For instance, the 2004-2007 Mazda 3 (my car) in North America is available with 2.0l, 2.3l, and 2.3l turbo engines, all four-cylinder. The fuel mileage varies significantly between these types, particular regarding the turbo, which often gets the heavy right foot. Thanks. :-)
We know there are a number of people who want more detail, but we feel like that would keep an even larger number of people from using the site. By striking what we feel is a good balance, we believe we'll all have more people reporting their data.
We know this means we lose some people in the process who feel like the data is useless without more rigor and structure, but that's part of the balancing act.