There are a ton of Priuses on American roads, which I think are a bit larger, will easily meet or exceed those fuel efficiency numbers, and do it all while burning gasoline instead of diesel. (Diesel is more energy dense, so it's easier to get better MPG numbers with it. Diesel is also more expensive in the US, so it's not cost effective unless the efficiency gain is significant.)

It's not all that hard to find efficient cars here. The Honda Civic is rated at 32MPG city/42 highway (and our ratings tend to come in a bit worse than real-world driving will give you), Toyota Corolla is 30/42, Chevy Cruze is 31/47. You can do worse if you want, but you don't have to.