First, let's listen to the song I always hear in my head when contemplating a tiny Subaru from the days before mall parking lots were full of the things. Dr. Demento was a big fan of this tune, of course:
I've driven a couple of these cars, and "underpowered" doesn't really do that 66-horsepower 3-cylinder justice. In fact, the only post-WW2 vehicle I've ever driven that was slower than the Justy was the VW Rabbit Diesel my high school used for driver training class.
But so what? This thing can probably cross several counties on a shotglass of fuel, and it proves that you don't need a Sprint for 3-cylinder 80s action.