A very simple but I think meaningful improvement:
For those with parking sensors, why do we have a graphic display of where the sensed object is but not an audible indication? We have over six speakers in the car, so making the sound indicating object proximity come from the direction in which the obstruction is would make it much easier to avoid a collision. Hearing a "Bong" when you are close to something doesn't do much in a car that makes more electronic noises than a Daft Punk concert, but having a sound coming from the specific angle in which the offending object is would make the sound stand out much better.
So the short version:
* Make object proximity noises when parking come from the direction where the object is by using the quadraphonic system in the onboard audio.