The Picanto is very fuel efficient. The manufacturer figures are around 56mpg. WHich is very good consider most car on the road in the UK do around 30mpg. Thats nearly doubled! I havent had any problem with my picanto yet *touch wood* and i have put around 3500 miles on it. It is one of the most rapid and cheapest 1.1i car you gonna find. If you want more spec for the car you could find it all on the kia official UK website. Hope that helps.
I measured fuel consumption when we first got the car (Picanto SE 1.1).
The fuel economy on the first tank of petrol was abysmal. We were averaging 6.5 litres/100km which is much higher than Kia's stated economy of 4.9l/100km combined, and that included a lot of motorway driving at 60mph.
However as we have done more miles the fuel economy has got better. I am currently doing another measurement with a full tank and the tripometer set to 0. The car is on 550 miles now. IIRC It is also known that cars tend to use more fuel until the engine has bedded in. My colleagues economy improved after he had done 2000 miles in his new car.
I will let you know what the efficiency is like next week.