We have just extended our lease for another 2 years, having done nearly 45k, I think the deciding factor was the AP we paid which was £2,999. When I called them they asked about the mileage etc, I also said that there was nothing suitable on the scheme and wished to extend. No problem all I was told was to make sure MOT is done, insurance is taken care of, however they did say that I could not extend over 5 years.