What would the point of this be? Are there upsides or downsides to adding this? I mean at that point you might as well just change the text on the userinterface or something of the matter, this sounds redundant.

unlikely the user who posted above will look back, but to put it here for anyone wanting to know. Diesel is generally more fuel efficient and more pricey (engine & fuel price). Whereas Petrol (Gas for you Americans) They are generally less fuel efficient but offer more kick and can be quieter

We need race cars

I think adding gasoline just makes sense, and would open up a new set of engines (like the small/medium/large engines already added) labeled as "compact" engines (in "V" piston configurations instead of inline, and would be overall smaller but use (these are just suggestions) say 10% more fuel and produce 85% the power, but are more rectangular in size (like {Height/Width/Length} 3x2x4 blocks[small compact engine], 4x5x6 blocks[medium compact engine] and 5x5x8 blocks[large compact engine])

This is just to try and build on a possibly implied use case for adding gasoline as a fuel type.

Currently the basic implemented (non-modular) engine sizes go [Height x Width x Length] 3x3x3 for the small engine, 4x3x7 for the medium engine and 8x5x11 for the large engine.

So my suggested dimensions for a set of "compact" engines that run off gasoline would actually be pretty good. though the medium ones would be practically the same size (oh well).

Also these compact gasoline engines could come with built in cooling systems that only need access to a fluid coolant reservoir (like a small fluid tank filled with fresh water) with a more logical placements of the exhaust and air ports.

This is just a few thoughts to build on the initial comment of "why"