I got excited when I read this (sad I know) mainly because I wanted the MPG side of it as my SX doesn`t have the onboard computer.Then I read the manual and setting it to read the MPG everytime you fill up and then adjusting the percentages.I wonder why it doesn`t read this straight from the leon like it seems to do for almost everything else,surely it must be there or do you have to do this with the onboard computer?