I would think adding a couple more garage doors would be much less expensive than adding rails and plates and whatnot. Not to mention so much easier than playing Tetris with the cars.
But my thought would be 2 rails sunk in the concrete run cross ways in the garage, each side car with a steel plate the size of a car mounted on rollers that sit on the rails. Probably need to devise a ramp of sorts to get the cars on and off..
no way to open up more entrance space, also the costs to do that would be so much more than you imagine...not to mention i'd have to file for a permit...and cover costs for an architect... based on my situation , permit would probably be denied anyways
rails in floor mean that the upper part will need rollers above the floor and the design will be a superposed one
im looking to possibly incorporate the roll-system inside the metal profile as to finish with a 'sleak' low to the floor metal ramp/plate (possible max. 2cm above the floor)
perhaps i should work with an 'open box profile' ( C - profile ) and put it vertically onto the 1 layer of floor, slide the rollers from within...
or maybe a U-profile type sunk in the floor, filled up with metal balls and a straight metal plate (balanced somehow) so that it slides over the balls from one side to another