Watch the Bring a Trailer auctions and you get a good idea about what is getting valuable. A BMW 540i E39 just fetched something in the mid-high teens.

Datsun Z's are going up. I wouldn't doubt the the 280ZX will start going up soon too.

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'07 Yukon 2500
'13 Subaru Outback 3.6R
'13 Orbea Carpe 9-speed

Currently Benzless
Formerly: 300TD, S600, E55, 560SEL

---= The forest breathes, listen.
-Native American elder