660cc engine at ~40 horsepower is about the same as a mid-70s VW Beetle - not in cc size, but HP potential.

This little truck could do a lot more than 25 mph if it were allowed to do so. Not saying that would be safe, and I'd not want to ever put one on a busy freeway, but for getting around most urban cities in the US it's fine as-is but would be even better if the limit was ~40 mph.