Well that was a fun afternoon.
The Prius 1st. Not the best looking car but very light & air inside the car & lots of gizmos to play with ...lol. As DC stated the engine runs alongside the battery, although there is a button to go to battery only for town driving as long as you stay below 30mph ....above that that the engine kicks in. Stopping at traffic lights the petrol engine kicks out, which freaks you out at 1st. The gear knob has been replaced by a small joystick affair on the dash .... you push it down for "Drive" or up for "Reverse" . Being a variotronic drive, the revs stay constant when you accelerate hard ..... quite a weird sensation.
On a 20 mile drive of country roads, town traffic & motorway I managed 48mpg ....not sensational vs some diesels these days. The Auto box makes for very relaxed driving , which is earily quiet at normal acceleration, but I must admit the engine does screa a bit on the motorway when you want to overtake something. I suppose the most attractive thing about it, is the amazing low CO2 emissions, which make for very low Company car tax. This car would cost £1K less a year in tax than RAV
