My example:
Wife and I went to the dealer that we bought our last 2 trucks at. She wanted a new car so I figured I would get a deal as we did with the truck. Well, it took 5 hours and the wife was impressed, but very tired. We were trading in her 2000 Isuzu Rodeo 4x4 that had a wholsale value of $6800 and a retail of $9500. The trade was in new cond as the eye could see but was a real TURD as far as being reliable. (Isuzu has no dealers within 250 miles of my home). Anyway, the wife picked out herself a new Chrysler Sebring convertible. Sticker on it was $31,000. Totally loaded. I started off telling the salesman I would give $12k and my trade. He laughed. The first offer on my trade was $5,000. . We started to walk. Hours later, the trade went up to $10k and I agreed to $14k that we would pay. That also included the "lifetime oil changes" and the 7 year, 100k 0 deduct warranty, and

$6,000 in rebates

. By 1 hour after closing, we left and was told to come back in the morning to finish the paperwork. I arrived at 8:30 and wasted another 4 hours but the wife was happy. The kicker was I forgot my checkbook. They said no problem. Yeah, right. When Monday rolled around, I showed up at the dealer and was going to pay off the balance and they had already financed the car balance. I was a bit upset but didn't have the time to argue as I was short on time. Later that night, I discovered that I got cheated out of a few more rebates. $1,000 for financing, another $500 or so for the wifes college grad rebate, and a few other minor things. I hit up the general manager and he was slightly P-O'ed at the salesman. They actually made good and cut me a check!(10 days later) Then I made my mind up that I didnt want to "pre pay" for my oil chenges as it would take about 100k miles to break even. I never keep a car that long. I sold the oil policy back to them. Well, after all was done, I got the new car for just over $21,000 less my trade of $10k, as there also isn't any sales tax here in Oregon. Then the real kicker was that i paid off the note before the first payment was made!
End of story is, do the trade. They will most likely end up giving you top dollar if the trade is clean and marketable. (clean CTD's are rare in most areas and never last on the dealer lot) Then you won't have to deal with selling it yourself and doing the million test drives and staying home countless days waiting for the guy that says "he will be right over", but never shows up!
Sorry about the long post