This paper is for bikes really, but the application is pretty relevant to any classic car/bike with an old fashioned dynamo/alternator power output. Interesting stuff
This is a proposed requirement for self levelling and washers for HID 'replacement' lights which are fitted as an after market extra. This isn't an MOT rule yet for this year - but you can bet it soon will be. So I'd think twice about investing in HID lights for your Mini.