Kind of a longshot but i figured i would post this here. Imagine the kind of mileage you can get from a 1 liter..... https://www.ebay.com/itm/273508469882?ul_noapp=true
I like the car , but not the transmission. Makes me wonder about what else is out there ( over 25 yr old JDM cars ).
The car is geared so that the revs are pretty relaxed. That said, they do make these in a 5 speed manual, but they are not as common. There are a fair number of Kei vehicles over 25 years old that have been imported. Kei vehicles are going to have 550CC or 660CC engines in them. Like these for example: https://unusual-auto.com/vehicle/26805-1988-suzuki-alto-works https://unusual-auto.com/vehicle/27369-1991-honda-beat