I solved two problems, my old metal ramps were hitting the plastic in the front of the car and they would slide. I got some 2 x 10’s and have a 5’ base with a 4’ piece nailed on it, then a 3’ piece then a 2 'piece, then a 1’ piece. It is a gradual series of steps vs a ramp, but gets the job done.
I no longer hit the plastic when I go up the ramp. I put a block of wood at the end as a stop. I store them against the wall in my shed. Pretty inexpensive. Do not have to worry about rust. I have seen some plastic ramps that I would not trust.