How do you do that please??? I would love to make my UCD car new.
The trick will not reset the mileage on a used car all the way back to 0. What the trick does is it resets the mileage back to whatever mileage you have before you enter a race, so if it’s a brand new car with 0 mileage on it, it will of course reset it back to 0. Essentially, it prevents you from racking up miles on the car and therefore keeping oil, engine, and chassis in the same conditions as before.
To perform the trick, before exiting out of a race from the race quick menu, just bring up the car setup screen (see screenshot below; no need to go into the detailed setup screen) and cancel out of that screen. That’s it. Once that's been done, your mileage is reset to the same mileage as before you enter the race. So say you enter a race with 1,000 miles on the odometer already and then do an endurance race for a few hundred miles. At the end of the race before exiting out of the race quick menu, if you do this trick, it will reset your car's mileage back to 1,000 miles, even though you've just raced for a few hundred miles. If you don’t or forget to do this before exiting the race quick menu, all the mileage you incurred during the race will of course be added to your car’s mileage.
AFAIK, this trick works for single-player races and even online time trials.
One anomaly not related to the trick that I’ve noticed is that if you change your car setups in the garage, that for some reason bumps up the mileage by a few miles, even though you have not driven the car yet and are just tinkering around with car settings in the garage....
