Nice and easy, but easy to miss.
Offline Road Rage's have no set course, so as long as you don't crash, get taken down or run out of time, keep an eye on your map and make your way to the nearest wrench icon.
Hitting takedowns will keep your time up, and as long as you steer clear of any on-coming traffic and shunt before you're shunted your route should be nice and clear.
If you're worried about missing the turn-off to pass through the Repair Shop, when you're close you can keep your eyes on the road, as there are usually at least 2 large colourful signs for each Repair Shop directly over it's entrance. Only thing to be wary of when you arrive is cutting across the traffic to get to it, but even if you undershoot and ram into the barrier or miss the turning, you will respawn in the same area and the other racers seem to leave you alone if you slow down and stay out of the way.
You can get this trophy while failing the Road Rage.
*** Spoiler - click to reveal ***There is a Road Rage the White Mountain area on Sunset Valley that starts right next to a Repair Shop. Just 180 at the start and drive on through