SargeCassidy

First of all - this achievement requires Title Update 1, as TU2 broke it by including 2 unreleased cars to the requirement.

There are 43 cars in total to drive, most of which are available in the Race Day which is going to be the fastest way to get the credit. To make sure it's counted, drive at least 2 miles/kilometers then crash out and retire.



Some of the cars are not, however, you can select the events needed for them in Online multi-player (or grind the World mode, though that will take you MUCH longer):

Once you meet the requirement (43 out of 45): clear your drive's cache, remove Content Cache and connect the drive you have TU1 on. Upon crashing out with any car again, the achievement will pop once you're in the loading screen.