Well perhaps warning is a bit much, but I saw an article recently where renters were given an electric car without being told and without any kind of training, help or guidance. I know it seems hard to believe, but heck if you're not really a car person and you're tired from a flight and you just want to get in your rental car and go ... well take a breath or two and make sure you know what you're getting.
And also the age-old advice to make doubly triply sure you are getting either a gas or diesel car in Europe. It makes a really big difference. And you can't tell by looking, I had a car salesman swearing up and down a while back that we were test driving a gas car, I got out and opened the fuel door and showed him what it said. He didn't know, and didn't care.