The GEM cars are frequently seen as being little more than a golf cart. They are what's known as a Neighborhood Electric Vehicle (NEV) meaning the speed is limited to 25 miles/hr. By being an NEV the safety requirements are lessened, I think.

GEM (Global Electric Motors) cars generally are open to the air, in that there are no doors. The speed is limited to 25 miles/hr, range is quoted as 30 miles, and you can get a series of options such as doors, heaters, air conditioners, radios, covers, etc.

Home page: http://www.gemcar.com/

Here are two companies specializing in accessories and speed enhancements for these and other similar cars:

Lincoln Golf Car http://www.lincolngolf.com/parts.htm
Ride for fun http://www.ride-4-fun.com/