I would try the "learn" sequence so you have the best possible alignment of the sensors to the control unit just for grins.
I carry my Cabrio often in the garage of a motorcoach. I like the car being backed in so the little bit of engine weight is more toward the coach rear axle line. This means backing up a ramp whilst having it centered in the garage and stopping at just the right spot and hopefully not driving through the wall and stuff like that.
This seems to work just fine as long as I use the hand brake to control the car and keeping the revs up. If I use the foot brake then goofy stuff happens with the reverse creep or sumthin and it makes me nuts. With hand brake control all is well and loading the Cabrio up the ramp is a no sweat deal, even with wet tires and such.