I never considered renting a car to be a particular security risk, but in this age of electronic everything, that's changing. The Federal Trade Commission warns:
When I rent a car, it’s fun to get all the bells and whistles – like navigation, hands-free calls and texts, streaming music and even web browsing. But did you know that cars with these features might keep your personal information, long after you’ve returned your rental car? Here are some things to keep in mind when renting a connected car.
What happens when you rent a connected car? When you use the car’s infotainment system, it may store personal information. It may keep locations you entered in GPS or visited when travelling in the rental car – like where you work or live.
If you connect a mobile device, the car may also keep your mobile phone number, call and message logs, or even contacts and text messages. Unless you delete that data before you return the car, other people may view it, including future renters and rental car employees or even hackers.
There's more at the link, including helpful hints on how to minimize your risk factors.
Seems to me that the so-called 'Internet of things' is more trouble than it's worth . . . but then, I'm a dinosaur. I actually believe in that old-fashioned value called 'privacy'. What do I know?