[Tannaton]

So we've been a Volvo family for some time and in the past 30 years between myself, mother, father and sister we have had: 240, 740, 850, 440, 480, V70 (2), XC70 (2), XC60 (2), S40, V40, V50 (2), C70 (2), C30, V60 and XC90.

My point is that all of them - except the XC90 - have 2 bulbs in each rear light cluster for the position (side) light. Why Volvo decided to put only one in the XC90 when there's loads of room - I don't know why. It's a really useful feature, a single bulb fails but you are still safe and legal.

Anyhow I removed the nearside rear cluster on my XC90 this weekend to dry it out as it had condensation in it and to investigate whether I could replace the brake light bulb with a twin filament 21/5w lamp to create a second position lamp. That's going to need some modification as the lamp holders have difference bases so you can't get them in the wrong holes - but I noticed that the side lamp itself is already a twin filament 21/4w lamp - but why? And why only 4w not 5w?? The brake and fog lamps are separate - what is the 21w filament used for?

It's of no real consequence but if anyone has any ideas... I'm really curious.