Hi,
my most useful gadget is an implement called a "handy bar". This little wonder helps me getting out of my car. It's an elongated T-shaped tool with a foam covered handle with the business end almost like a mini pick. what happens is that when you want to get out of your car, you place the end of the bar in the lock piece which is located on the door pillar of the car. In this position the bar provides a means of pulling yourself up form your seat and then by shifting your grip you can use the bar to steady yourself until you've gained your balance.
The handy bar is available in Halfords and Argos and costs around £22.
Regards,
Jaykay