Today I traded in a 03 Durango 52,000 mi w/3rd row seats for $6125 for a 05 Ford 500 w/27,900 mi for $14,700?

Could you tell me if I was ripped off? The Ford Five Hundred SEL has a 6 cyl, driver airbag, cloth seats, is front wheel drive, a 6 cd changer and is automatic. My Durango that I traded in had 4 wheel drive, single cd player, p/w, power seats, 3rd row, roof rack and was an 8 cyl.Also still had factory warranty and one year left on my standard used car dealership warranty. I have 3 days to return it. Was suckered in quickly... Paid $16,000 for the 03 Durango two years ago. Paid $14,700 for the Ford Five Hundred today and only rec'd $6,000 for trade in. Dealer told me that was the Kelley Blue book value but it doesn't appear that way. Started the price for the Ford 500 at $18,995 and let me negotiate from there. Please advise asap so that I can ret'n if need be. Reason for trade and purchase is low mpg on Durango. They told me I'd get about 20 mpg with Ford 500. Any idea if that's accurate?