Twelve horsepower for a 198-pound car is like 144 for a 2,400-pound car, except if you have a 151-pound driver, and a 151-pound passenger, you are then at 12:500, compared to 144:2,702; 2.4%, compared to 5.33%.
These "bubble-cars" look funny. But if I were seriously looking into get a Peel Trident replica, I'd probably rather get a 150cc engine out of a Honda PCX instead of a 50cc, and to make it a single-seater as it's too narrow...