Our last Motability car was a VW Tiguan 2.0TDi 190 DSG. There were a number of things that really irritated me about the car, mostly because the VW technology didn’t work half as well as the same systems on a BMW that I was running at the same time (or, indeed, as well as the BMW that we replaced the Tiguan with).
Whilst most of these things were just how the VW systems work (and why we didn’t order another one), one issue was downright dangerous and it was the radar emergency braking system. On three separate occasions the car applied the emergency brakes for no reason – once on a motorway (which could have been fatal) and another time in heavy rain when a van had been tailgating me but had thankfully turned off seconds before. If it has happened moments sooner he would have rear ended me.
The VW dealer (who was useless) had the car in twice, cleaned out the sensors and recalibrated them, but I was always wary that it might do it again. After one of the two most serious incidents I called Motability and said that I was having to turn the system off manually every time I drove the car, which was far from ideal (as I’d sometimes forget) and, whilst I am a very experienced driver, I didn’t feel confident driving it. They agreed that if I wanted to they would allow me to change the car early. As by this time we were in the last year of the car I stuck it out, but I was very glad to get rid of the car in the end.
As others have said, you have to give VW a few chances to sort it out, but if they can’t I think that you will find Motability to be sympathetic. The issue then, of course, will be lead times on whatever you replace it with as, rather stupidly, Motability don’t recycle perfectly good cars that are also returned early.