This is a frequent request. If you take a quick look through the forum, you'll see this conversation come up quite a bit. We know there's a demand for more sorting options, more filtering, more precision in listings. We know some people see Fuelly and want it to go in this particular direction, but that's not the vision we have for the site.
Our overriding goal with Fuelly is getting the most people possible tracking their fuel usage. Along the way to that goal we get a lot of interesting data to look at. But the data isn't our primary reason for existence. We'd rather see more people tracking with less precise data than less people tracking with more precise data.
We feel like taking the site in a direction that requires and displays more detail from people will alienate many users. We're comfortable with the current level of detail because we aren't trying to be the ultimate source of precise data about fuel economy. We explain this a bit more in the FAQ: Why don't you track more vehicle details?