first you have to have gta v save editor, horizon, and hxd.

Now go into Horizon and extract your gtav single player save onto your desktop.

next open gta v save editor and open the save, then go to michaels garage.

make the second car and have a license plate name you will remember. now make the fourth car whatever you want the nos to be on. (Franklins buffalo) is the fastest.

now press save file in the top left of the save editor. After that is done click on block and extract the PSIN file.

Take the PSIN file and open it up in Hxd. press ctrl f to search for the license plate name for your second car. once there go down 10 rows. On offset 0001c690. once there go three sets of zeros to the right, on the fourth set there should be number 11. change that number to 1c.

then save that Hxd no need to replace the other it does it automatically. now take your save and put it back onto horizon and save it back to the usb.

take it back to gta v and do the sp to mp glitch and have fun!