But look for discounts on pairs. To give an idea of just how much extra light HID bulbs put on the road, we tried Osram’s standard performance H7 bulb in a VW Golf Mk6 headlight. The arc burning ...

To complicate matters, both varieties are available with xenon-look blue coatings, as well as with 30 or 50 per cent more light ... H1 or H7. If you must buy a standard bulb, go for Unipart.