Car Mechanic Simulator

This is one that you could possibly get through natural progression - depending how much time you are potentially going to put into it. However, for those that want to grind this out you can follow the steps below.

Process:
- Sandbox Mode
- Upgrade your garage to max via Toolbox
- Upgrade your Parking to max via Blue Door (Exit to Parking and selecting each level individually to purchase, up to Level 13)
Whilst doing this you will also get the achievement for upgrading your parking to Level 10

Below are the repeatable steps
- Go to the main garage door (Map)
- Car Salon
- Purchase all 3 cars and send to Garage or Parking
- Return to Garage
- Repeat until you have 100+ cars (34 times)

Next Process
- Approach a car in the Garage
- Quick Menu (), Car Status, Sell Car ()
- Next Car, until Garage is empty
- Blue Door (Parking), remove 2 cars from the Parking lot and repeat selling of car
- Continue repeating Parking to Garage to Sale

You will unlock the "Sell 25 Cars" and this achievement ("Sell 100 Cars") through this process.

I would recommend playing the game for the other achievements before attempting the "Sell 1,000 Cars" achievement, simply because it would take a long time and become very tedious - or maybe do it in small doses between your other achievements.