I have decided to sell my 300SL solely because I want an automatic instead of a manual transmission. I'll probably replace it with a 500SL, since the 300 automatics I have driven are sluggish compared to my current car.

I'm posting because I can't get a handle on what these cars are worth. Book values are at odds with what seems to be transpiring in the marketplace.

Going to KBB.com and punching up a '91 300SL with an Atlanta zip code, excellent condition, and 120K miles gives just $13,575 for "private party value". Yet looking at classified ads suggests the market prices are much higher. The Atlanta Journal presently has a '91 300SL with 110K miles for $20,700, and the L.A. Times just recently had a similar car at nearly this same price. These two cars are typical of the classified market. A glance at the ads on www.cars.com affirms this observation. And on eBay, where sellers are inclined to sell bellow market, cars very rarely trade hands for less than $15,000.

I think the KBB is way off base with its “private party value” of the 300SLs. And for that matter, the 500SLs as well. I would guess a typical 300SL is worth $17K - $22K. And within this range, I think the price is more sensitive to mileage than model year. I believe a ’90 with unusually low miles is worth more than a ’93 with extraordinarily high mileage – contrary to the KBB.

Any opinions will be welcome.