I was wondering if there were any plans to break down the models perhaps by engine and drivetrain type. For example, the Cobalt I drive was offered with 2 transmissions and 4 engine types ranging from an economy 2.2L to a turbocharged 2.0L performance engine both vastly different. Similar to say what a Caddy CTS (6cyl auto) would get versus a Caddy CTS-V (8cyl 550hp manual).
I believe this information would be quite helpful. Perhaps, similar to how Fuelly works, entering in the max capacity of the vehicle's tank and amount of gas it took... actually, if you keep track of your gas mileage it's pretty easy to determine how far you can go once your light comes on.