First park your car in the garage, press f8, go to object spooner, and turn on spooner mode. Then take the marker at your car, press the up arrow. Now your car is saved to the entity database. Now go to object spooner, manage saved files, and click save database to file. You must enter a name, for your file, and a reference spot. Now, everytime you restart your game, go to object spooner, manage saved files and load the file you saved. I hope it would help.

If your game is crashing, install heap adjuster and packfilelimitadjuster.