I just made a test build for this challenge - an FF hatch with a 1.8L DOHC NA I4 delivering 100 bhp in a sub-850kg body. So far, I’ve managed to get 26 US mpg with the use of a 5-speed manual gearbox, mechanical fuel injection, and a 3-way catalytic converter. That said, getting >25 US mpg with a 3-way cat and regular unleaded in 1979 is a challenge (especially since multi-point EFI is not available until 1982) - but 26 mpg is more economical than what most contemporary muscle or pony cars could manage.
1 Like