Truck Racing Championship

If you don't get this naturally, you might need to grind out a few more km at the end. You should be at around 400km minimum by the time you've done done everything else. You can check your progress by going to Main Menu->Extras->Stats.

Go to quick race and choose the track Canadian Tire Motorsport Park - this track has lots of long straights and not many difficult corners, much of it can be done at max speed. Use the following settings to make it as easy and fast as possible

Laps - each lap is 4km, work out how many you need
Start position - 1
AI Difficulty - super easy
AI Drivers - 2
Speed Limiter - off
All penalties - off

One lap will take 1'40-1'45. Achievement unlocks when you finish the race, not during