I’m looking for ultra-high-mileage cars. I don’t mean like the Geo Metro (mass-produced by a major manufacturer), I’m talking about obscure European brands that have been imported into the US, or manufactured here in limited quantities, or manufactured by US manufacturers that have gone out of business, etc. Like the Reliant Robin (70mpg), the Solo Single (150mpg when battery is considered), etc. These cars are unique in multiple ways - some have a single front seat, some have three wheels, etc.
I’m also looking into homebuilt cars like this - like, some guy retrofitted his motorcycle into a highway-legal tuktuk, or whatever.