Turn points into seconds for the last race of the season. Driver A has 300 points, Driver B 250, Driver C 200. So Driver A gets a 50 second start over Driver B, and 100 seconds over Driver C. Winner of the race is the champion. So whoever is leading, is leading the championship, whoever is 2nd is 2nd. No need to work out complex points systems like adding 25 to the score as the maths are all done for you right in front of your eyes. Simples.
I like it. You win the 19 first races out of 20. In the last race your engine eats crow. You're out.