This should, and likely will be, the last achievement to get. Unless you really need it for some reason wait until the end to grind it out since you'll knock out a good 25% or more getting the others. If you don't want to wait for this to come over time then there is an idle method below.
This can take as long as 8 hours depending on how much progress you've made before hand.
Idle MethodStart an Exhibition match on any map with no bots. You'll also want to adjust the Mutator settings to these:
- Match Length: Unlimited
- Boost Amount: Unlimited
- Boost Strength: 10X
- Maximum Score: 1, 3 or 5 (This is the only way to end the match. It's not required, but as long as this takes it's good to have a way to guarantee a progress save if you need to stop.)
In the match, tap the ball into a corner so it's out of the way. Now, return to the center and get the
(left stick) turned all the way left or right with a rubber band or tape. Then rubber band down the
(boost) and
(powerslide) buttons. You may need to wedge something under it to get them fully pressed. This will leave your car doing a never ending doughnut on the field. You can simply
plug the controller into a charging cable while it goes in circles the whole time without you around.
NOTE: JORAX points out in the comments that you can bind the Powerslide and Boost to the triggers to make it easier to rubber band. Go to settings and tab over to controls then bind each to a trigger for an easier way to set this up. Just be sure to switch it back after you're done if you want to play the game.
NOTE 2: Fleshwrither mentions if you start receiving no progress you should try using only the normal accelerator (
) instead of the boost. If this fixes the problem try to add the boost to your setup to make it go faster. Just verify that progress doesn't stop again.
Additional InformationYou can check your distance by going to the garage and selecting tires. Each tire tracks the distance covered while using them. All 50 KM do not need to be done on one set of tires. Mine unlocked with one set at 43 with others filling in the rest. Some people have mentioned going over 50 KM on one set before it unlocked, so it isn't a bad idea to stick with one until you've completed this.
The tracker in the achievement app doesn't work all the time, but it will progress by closing the app and re-opening it or once the achievement pops. There are issues though, so refer to NOTE 2 for a possible solution.
EDIT 1: Adjusted for clarity and added more information.