I don't think many people would complain if you split out the engine layout from the fuel type. e.g., the car would simply be identified as 'gas' or 'diesel'.
You *could* then add an optional 'advanced' section where you show 'engine layout: inline-4' or other wishlist things such as displacement (this would not appear by default but would be enabled by the user).
That way you keep it simple for new users, and advanced users could add the extra information without complicating the interface for everybody else.
Late update sorry, but also an option for turbocharged vehicles would be good. Turbo vehicles tend to use more gas than their naturally aspirated cousins, so differentiation between the two would help.