Had a mark III prius as a company car for the last 10 months.
Its averaged 52 mpg over the 11000 miles its done from new with me. Day to day driving is all urban and suburban, but I’ve done a lot of road trips in it. The worst mpg it gets is high 40s in very cold weather for short urban journeys when the engine seems to run more for heating the cabin/screen. The best i’ve got was drving from the midlands to north wales – a mix of Mway and A roads in the summer gave about 65mpg.
The interior has lots of space, and certainly more leg and shoulder room than a focus or golf. Its very relaxing to drive. I have had zero reliability issues.
I can’t comment on servicing costs as i don’t pay them or even see the bill. As a company car its great.