23 Dec 2013 23 Dec 2013 06 Jan 2014
Just an addition to the other awesome guides here.
Found a faster method which requires very less effort.
Works on the latest patch where are Drag races were added.
What you want to do is, race with a dummy account, whcich has your tuning setup and design on the car. In free play.
Instead of using Circuit races select Drag (by pressing 'right' at the Game Oprtions -- Game Type)
Game Type: Drag
Max AI: 1
Drivatar Diff: your choice
Drive Type: Any
Assists: you want to select Automatic shift
What I did:
I taped down the RT and watched some movies on my other TV and just selected Restart.
Takes about 1:00 minute to complete 1 race including all loading screens.
EDIT::: You have to do at least 80-100 races in one DAY ( I think the Forza Server counts from 7pm PST- to 7pm PST next day) to get credits for the races.
I made 330 races in ca 7-8hrs and earned 70k for tuning and 25k for desings.