Wow you've parked in car parks as a bike and got away with it? Well, that's my decision to purchase a Twizy solidified then!
EDIT: Found this: http://forums.pepipoo.com/index.php?showtopic=74350
EDIT 2: From what I've read from Gov legislation, the Twizy is classified as a 'L7E Heavy Quadricycle' not a L5E.
EDIT 3: OK, I think it's best to read your local councils definitions of spaces and who can park in them. My local council lists motor cycle spaces and motor vehicle spaces separately. With no mention of quadricycles, it only mentions the Road Traffic Act 1984. Reading this, there are only definitions of motor vehicles and motor cycles (less than 4 wheels.)
However, it would be interesting to have a chat with my local councils legal team about what can and can't be done.
EDIT 4: From the state of Guernsey: https://www.gov.gg/CHttpHandler.ashx?id=103536&p=0 "Quad bikes are not considered to be motorcycles and are not entitled to use
motorcycle parking bays. Vehicles must be parked in car disc parking spaces and
must comply with the disc parking regulations. If there is no secure place to display a
parking clock on the vehicle, arrangements should be made to provide such a place
(such as a waterproof bracket) before parking in a disc zone."