The City El was originally produced in Denmark and had been around since 1987. The early series I City Els (or Mini El City as they were then known) had simple resistor-based speed control and had all 36v electronics including the lights!
The series I Mini El isn't really up to daily driving as it doesn't use a modern controller and has parts which aren't interchangeable with later models. It also has a slightly different roof and front light arrangement. It also has a front parking brake operated by the foot instead of the normal handbrake.
Series II and onwards (some Series II seem to be called Mini El and some City El) have 36V traction systems and a 12v DC to DC converter to run regular car lights. The name was changed back in the 1990s when I believe BMW got snotty with City Com for using the word 'Mini' in the name. I may be wrong of course!
The series II and series III City Els are quite often on ebay in Germany (
www.ebay.de) If you speak German or don't mind doing a bit of school translation you can get quite a bargain. German City Els made prior to 1997 don't need an SVA on import to the UK but ones made after that do. Mine is a 1998 model and there are some other post 98 City Els on the road in the UK.
Expect to pay between £1,000 and £3,000 for a good City El in the UK that has already been imported and such. German ones can be picked up for anything from €1,000 upwards.
Bear in mind that the City El is a car which was designed and primarily used in very flat countries. In their native Denmark or indeed Germany you can quite easily get 30 or 40 miles out of a City El, but for me in Bristol (which has a fair share of large hills) I'm getting about 25 miles maximum.
If you do want a City El (and they're great fun) I highly recommend either buying one new (which starts at about £6,000) or finding one which either has a 48V battery pack (higher top speed) and a lynch motor (fact four) drive system.
The regular ones will work, but after living in Bristol with a bog standard 36v model I'd advise a more efficient and higher voltage motor would make a big difference.