What is the fuel economy (mpg) for a P reg Fiat Punto (1.2cc)

You should get between 35 & 40 mpg. Of course, fuel economy depends on the way a car is driven and the condition of the car. A sensibly driven, well maintained Punto 1.2 will return these sorts of mpg figures.

l had a 1.2 Punto once, & it had a little trip meter that could show mpg. It took a reading every 30 seconds or so. The best l ever saw was 97mpg (5th gear, 60mph, downhill, off the gas) & the worst ever was 22mpg (standing start, flat out up to 70mph, up a hill) It averaged about 35-40mpg in town, & 50-60mpg cruising at 70-ish mph.

it should be around 50 miles per gallon