To achieve this, you will need:
A car in your garage that you can sell （JUST BUY THE MOST CHEAP ONE）
Cheat Engine on your computer

1. Step1
   : go to your garage and pick a car to sell (don't sell now),remember the price
   
   
2. Step2
   : open Cheat Engine
   https://steamuserimagesa.akamaihd.net/ugc/2004695120353090651/5F8B84B097391EFA68335D8FD80AB3609D98CAAB/imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false
   
3. Step3
   : select NSF Unbound, and search for the selling price of the car.
   
4. Step4
   : select all results, and change into 99999999999
   
5. Step5
   : sell the car, and you get the money

https://steamuserimages-a.akamaihd.net/ugc/2004695120353100774/D4FFC2A2BCAF9F8E69CD2CB0A10ECFE584CC823F/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

https://steamuserimages-a.akamaihd.net/ugc/2004695120353100205/BB8022E8979DB654F809CCC2FD9BD03CCA4B28F1/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

enjoy