Wreckin' Racing mode is the main atraction of the game, yet it's a bit of a hell in terms of speedrunning due to how RNG dependent it is, as you can't control the points CPU cars will get, which drivers will be on 1st in each race and thus be the ones you'll try to score points against (the lines that each CPU car follows are a bit different and there are cars that are easier to score points against than others), and how they will behave. This means it's hard to know how many points you have to get in order to be safe to win the division and how many tracks can you skip.

However there are a few possible strategies that can be done in order to reduce uncertainty, and be able to skip the maximum number of races while still promoting:

1- CPU will get way less points on average on simulated races than in full lenght races. I noticed this after many races and simulations of whole seasons, in the simulated seasons the CPU cars almost never got to 100 points (division winners being between 60 and 100 pts, even for div 1), while in the ones where I played every race, they often got to 200pts. The circuits where the CPU usually get the highest scores, Crossover, Cactus Creek and Bowl are the ones where this is most noticeable, specially in the Bowl where there are usually CPU cars that get up to 70-80-90 points, while if you abandon the race just after it starts and let it simulate, the first car will be around 40-50pts. This way, it's optimal to skip all races with crosses and the bowl and instead race in the circuits where CPUs struggle to score.

2- When abandoning a race, the last CPU car that hits you will be given 10 points as if they had just eliminated you. You can verify it by exiting a race just at the start. The last car that hits you will appear first on the live simulation screen. When skipping races in a championship, be careful not to hit any car in your division as you would gift them 10 points and make it harder for yourself to promote.

3- You can get a bit more than 99 points to increase your chances of winning the divisions while not playing more races. First, after abandoning a race, you get to play for roughly 3 seconds where you can try to score some points (but remember point 2, don't crash into cars in your same division!).

In the Bowl, at least in the PAL version of the game, if you hold X and LEFT at the start you will always get a 360 from Barmy Army, which add 10 points to your score. You can get these 10 points and then abandon just after (again remember the stated in point 2, as Barmy Army he will get 10 points if he's the last car you hit before you abandon. If you are in the same division than him it's better to hit another car before exiting the race to not play with fire).

By playing only a race where the CPU tends to perform badly and getting close to 99 points in it, then getting 2-4 points from other races and 10 points in the bowl, you'll be around 109 points, while CPUs will get results similar to the seasons where I simulated all races, meaning all division winners will most certainly be in a range between 60 and 100 points and you'll be first (it's still RNG and there can be outliers that f*** up your run, but most of the time it will be like that).

It's a bit risky as you'll have to perform really well in a single difficult track, and even then you'll depend a bit on the RNG but it's really feasible.

Now, we have proven we can win a division while doing a single race in the whole season, but which circuit is the best one to do so? As I said before, Crossover, Cactus Creek (1, 5) and Bowl are must skip. From the rest, choose the one where you feel the most comfortable and perform the best, as the primary aim is to try to get as close to 99 pts as possible. If you feel equally good with any circuit, then shorter is better for spedrunning purposes. As the number of laps of each circuit won't change even if the layout does, Cactus Creek (2-4) is probably the fastest race, as there are only 8 laps in a short square track. Speedway (1, 2, 5) is another very fast track, so a complete run could be:

Division 5 - Speedway Division 4 - Cactus Creek Division 3 - Cactus Creek Division 2 - Speedway/Cactus Creek* Division 1 - Speedway

*Riskier due to starting far back and only having 8 laps to get to ~90pts.

Ocean Drive and City Heat are also viable options if you perform better in these.