The first Prius were sold in Japan in 1997 (eleven years ago!)
The first exported Prius was in 2000 -- this was what is called (in this
NewsGroup) Gen 1. It was a conventional 4-door sedan style.
From 2004 on, it was Gen 2, which is most of what you see on the street
these days. It is 5-door (hatchback) body style.
Mine ('05 with about 63,000 miles) has averaged long-term about 49.6
MPG. I keep a spreadsheet that accounts for *every* gallon of gas and
*every* mile driven.
Far and away this is the best car I have ever owned.
Regarding batteries -- the only ones that have been replaced have been
due to accidents. There are stories of Prius taxis in Europe with
200,000-plus miles and no battery problems.