The height adjustment of the HIDs in the Audi TT is computer controlled (another example of German engineering overkill). There are sensors on the sway bars to determine the pitch of the car and adjust the headlights up and down to compensate for hills (a vertical version of the Tucker). I have see disputes of the consumer reports that they did not take this into account when measuring the distance.

In the UK the self-levelling mechanisms are mandatory for HID/Xenon lamps.

I've found most HID systems are implemented pretty well, but I guess one in four cars annoy me

In my Camaro the previous owner fitted aftermarket Cibie lamps and they are very, very good. On the Caprice the stock lamps are very poor - the pattern has many mishapen blobs all over it! It's made worse because I have to put tape on the lenses to cover the LHD kick-up. Unforunately the Caprice was never sold in RHD form and the best upgrade is a set of $400 glass headlamp units made by GM for the German/Middle East market. I'll probably get a set before this winter - it really does annoy me.

Gareth