I'm wondering what is the easiest way to give a car from one character to another (perhaps on the opposite side of the map). The garages can only be accessed from the owner and cars left without a character nearby may disappear. I remember reading something related to parking lots and car storage but can't recall the details.
If you set a waypoint for a character, then switch characters, the other character will generally head towards the waypoint. You can continue to check their progress by swapping between the two until they both arrive at the destination.
When you switch from a character he will generally stay where you left him for a little while. When you switch to a character he will spawn pretty close to his safe house. For Micheal that's usually in Vinewwood, Trevor is Sandy Shores, and Franklin is either Strawberry or Vinewood Hills.
You can use this to your advantage and drive to near the spawn location of the character you want to give the car to, and then switch to the recipient. He can then meet up where you left the previous character and take his car.
Caught on to this trick when I accidentally ran Franklin over with Micheal after leaving the latter standing in the middle of a street.
Edited to add:
Make sure the character you are taking the car from is standing a little ways away. I tried borrowing the Trevor Phillips Industries helicopter, and Trevor didn't like that one bit, pulling Franklin right out of the cockpit.
There is a pair of garages next to the Impound Lot (green lights). These garages open for every character and keep the car accessible. I was able to exchange a car between Franklin and Michael.
Theres an easier way, only one condition: -you must at least be to the part in the story where trevor takes over the strip club.
That being said, behind the strip club, kind of by where trevors truck is usally parked there are four or five parking spaces. Namely, two with yellow parking stops. Those are his garage spots, and the fact they are not enclosed lets any character can walk up and take as they please. The car will save there, promise. i put my z type there all the time and dont think twice.
I swapped cars between characters by calling them for an activity and got in the car after the activity.
In this case I played with Franklin and called Michael. I took Michael's car and after the activity I still had Michael's car and Michael walked away .
My best way of doing it was, if you park a car that you want to get rid of outside the x persons house, then when you choose x person you can drive to your house if you do it within a day of game time and the car won't be impounded. I done this quite a few times.
I took all the suggestions and this one works the best 100%. Take the character which has the vehicle you want to switch, lets say Trevor (T). Using him go to a location which is easy to find and close-by to both characters(I prefer the impound). Then using T go to this location with the car and somehow manage to get the car stuck, disabling it from going forward, (being able to reverse is fine). To do this you may jam the car inside the impound green lit garage all the way inside to a corner (hit the car on the wall). KEEP "T" INSIDE THE CAR. Now switch to the character you want to have the car lets say Franklin "F" now take F and drive to the impound with another vehicle. Once there jam his car towards a wall and not inside the garage.( while he tries to forward his car out you can make the switch). Now what you do is switch back to "T" and take the car outside, now get out of the car making sure to park in a park spot near "F" (not right next to"). Now get out of your car and get into another car with "T" (this is important as otherwise T will get back to the same car and drive off") the moment you do switch with "F", now the car you want is free and "T" drove away in another car. Go save immediately as this is a pain in the ass to do again ^.^
Easy way to do it: With Trevor, park at Floyd's apartment (while it's still his safehouse) next to the blue tarp. Switch characters and go to Floyd's with them. The car will be there for the taking!
Take your car to Denise's garage with Franklin. Go to the impound lot and the car you put in Denise's garage is still in there and its also in the impound. So you have two!