In general, the 12 cylinder engines from BMW and Mercedes will be pricier to maintain or repair. The 8's are more common but also have better reliability. I had a friend with a BMW shop and people pick up killer deals on used 12 cylinder cars but have heart attacks when they find out how much it will cost to fix. Unless the car has had it's maintenance up to date and everything looks good, I wouldn't risk it. If you do find a good example though, it is pretty exclusive to have a 760, and they're fully loaded with everything!

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2004 X5 3.0 White on Tan/Premium/OEM DVD headrests/DICE Mediabridge
2006 Nissan Armada SE
1986 Audi Coupe GT/5 speed
1992 Jeep Wrangler 4.0/5 speed SOLD
1988 Jeep Wrangler -SOLD and gone for good
1988 Honda Hurricane 600 - STOLEN