[pitaj]

I've thought about this, too. It can't be that difficult to do, can it? Maybe it's illegal under current regulatory systems.

[smileysteve]

building a tiny engine that runs efficiently and produces enough meaningful electricity to make up for its weight is difficult.

From a regulatory standpoint, yes, fuel systems would be regulated in this design.

[pitaj]

The engine wouldn't need to be especially efficient; it's purpose is to extend range, not to be the main charging apparatus.