A normal hybrid only does 5-10 miles on the electric motor alone. A PHEV does 20-30 miles on the electric motor alone. Both of them regeneratively recharge on a run. How much they regenerate is influenced by the way you drive and the terrain over which you drive. Toyota says that over big distances a plain hybrid Prius works out more economical than a Prius PHEV. But on a run of 100 miles or so we averaged more than 80mpg. It's worth noting that the current Prius steers and handles exceptionally well.