Surprising mileage on test drive

We took another Prius for a test drive yesterday, and I was frankly surprised at the mileage. This was late afternoon, and we got stuck in traffic a lot. Despite so, we got, except for the first five minutes, well over 50 MPG. I had expected more in the high 30s or low 40s under those circumstances. Each five-minute interval got steadlily increasing mileage, and after the first ten minutes, we were over 55 MPG.
Wife still likes the TCH better, we'll have to see. We still need to sell a house before we can jump on either car. I like the fastback design, and the hatch--she likes the amenities in the Camry. I still am not crazy about the interior and lack of driver input, but I do like the mileage, and I guess I could put up with the "office furniture from Pluto" interior!