Forza Horizon 4

Here is my solution:

You need at least 50 Carpoints. 1 Point is earned with 50000 Skillpoints.

how to get them as fast as possible?

1. Grab Ken Blocks Hoonigan Focus
2. I made some tuning adjustments for this car to make it even more aggressive and faster. just search for my gamertag and the "xp grind" tuning.
3. start to unlock every perk you can with this car. You can grab the "at one with the car" Achievemt too.
4. you can go berserk with this car at anyplace and any time. go to the windmill park and hit the throttle.

as soon as you unlock most of the skill perks you will see why i suggest that car. it is a xp machine. during 2 forzathon live events and driving it around i made 109 mastery points

besides: with my setup it makes a nice street racing car and it is a force to be reckoned with at each live forzathon event.

use this car to unlock all streets too. you combine the effort there with making a ton of skillpoints

A car mastery is a essentially a perk for that provides driving bonuses, gifts like wheelspins or credit boosts when driving a particular car.

Each car has multiple masteries, and each of these perks require from 1 skill point to 25 skill points to unlock, and you'll gain skill points by playing the game, particularly as you do drifts, jumps, skill chains etc.

The quickest way to get this achievement is to take advantage of the cheapest skills that each car has, there are three perks for each car that cost just 1 skill point each, so once you've got 50 of these points you can do the following:

1. Go to your garage, get a car and then go to the cars tab in the pause menu
2. Select Car Mastery and purchase the three skills in the bottom row that cost just 1 skill point each
3. Go and get another car from your garage and repeat the above until the achievement pops

It's worth noting that another achievement 'At One With the Car' requires you to unlock every perk for one car, so going for this achievement will give you some progress towards that, but it will cost over 50 skill points just for that achievement so you might want to focus on just one of these achievements first ('Master of Many' or 'At One With the Car')

This guide should help you to boost all achievements relating to earning skill points as well as significantly boost influence in the process.

Achievements Boosted:

Coronation Trickin' - Bank a Skill Chain of 195,300 or more points.
At One with the Car - Apply every Car Mastery available for a single car.
Master of Many - Apply 50 Car Masteries.