pt cruiser has 3 engine types:
Regular (2.4 l, engine), turbo (2.0l engine), and a diesel version (not made in USA).
Engine types updated on fuelly site by gas, turbo, diesel?
The fuel consumption of a diesel and a turbo engine are significantly different from a na engine.
Usually on the pt cruiser, the na engine gets anywhere between 21 and 25 mpg avg. The turbo (despite having a smaller engine) gets anywhere between 18 and 22mpg; and from what I've read the diesel gets anywhere from 28 to over 35mpg.
Those are some wildly different numbers!
I would suggest to give users more options to select as engine type,aka DIESEL, TURBO, and gas; not only for the pt, but I guess there may be more cars out there with different engine types (other than just a larger engine, like eg Nissan Altima that comes in a variety of engine types (eg,a : 2.0, 2.5, 3.0, and 3.5 liter).
You can filter by fuel type right now. If you go to any vehicle listing page, look for the filtering controls at the top. They look like this:
No one has added a PT Cruiser diesel to our system yet, but they can if they want to.
You're right that we don't track engine displacement (2.0 liter, etc.) or whether or not an engine has turbo. That's one of the decisions we made when we set up the site. We're not car geeks, we're web geeks who also happen to want to track our car mileage. We wanted to set up a site for people like us because we felt that the existing car sites were too technical. To even simply look up the mileage for our cars we had to look in our car manual to find out out very specific technical details that we didn't know off the top of our heads. That was frustrating, so we wanted to set up a site that was more welcoming to casual drivers. And part of that was paring things down to the essentials—and one person's essential is not necessarily another person's essential.
If we were doing science, or if the main goal of Fuelly was getting the most accurate reporting data we could, we'd want to track as many variables as possible. But we feel like the goal of Fuelly is simply to get as many people tracking as possible to get a sense of their mileage. We feel like keeping things extremely simple is part of that mission. Along the way we happen to get some stats to look at, and we try to give some tools to help sort by the variables we do track.