I reckon its because its a perfect place for a web, a nice cornery bit to attach it all to and a mirror to hide behind while they wait for the flies to get trapped.
My wing mirror spider had hung on thro many a fast journeys 'round West London ... then one day I caught of glimpse of him hanging on for grim death whilst I zipped along the Chiswick Flyover .... and as I was watching .... he flew off and disappeared!
I nearly crashed my bl00dy car! and was extremely upset about the whole thing for at least 30 mins! He'd been with me for weeks and I though we'd built quite a friendship up! I'd protected him from the Car Wash - and he left me in the middle of Chiswick - probably for aYummy Mummy in a 4x4!
. . . and I laughed at your response Morticiah.
Sometimes the light-hearted questions result in the best answers. I hope you didn't give your spider a name. This would be the early signs that you might be cracking up.
Spiders & (Fly) overs, that's why he jumped.
My Fiat Punto has a spider in the nearside wing mirror which absolutely refuses to leave.........My Grandaughter calls him Incy Wincy Spider as even the the hose pipe and carwash fails to permanently wash him out............I think the attraction is the flies that stick to his web as we drive along...........easy pickings for Incy eh?
It seems you guys have a bit of a thing going on here with this mini beasts....why not check out www.myspace.com/wingmirrorspiders - or - www.wingmirrorspiders.com you might just like them :o)