finding relative values

tali

question for any economists out there, i want to find relative values of cars(ie say a new rolls royce costing £5000 in 1965 would be equivalent to x amount today) and properties so which is the most realistic tool to use from here http://www.measuringworth.com/ukcompare/ , i assume its RPI , but what about gdp deflator and average earnings?-would an average of these 3 give a more realistic figure?
cheers