My sister-in-law is looking to purchase a new Ford Focus but cannot decide between the 1.6TDCI diesel and 1.6I petrol engines. She does less than 10,000 miles per year, mainly very short runs in town with little longer distance high speed (motorway) driving. I have advised that a diesel is not suitable, but others suggest that for economy and resale in five years a diesel would be better. Will economy for the diesel reach anything like the published mpg on short runs and will there really be a huge difference in resale for a Focus? What sort of damage will be done to a diesel with this sort of driving?