If you must know, it sounds high. New cars (Z06's) are $5,000 off plus your car is used, albiet low mileage say $3,000 off. Since your extras are not in the blue book, they have no value for lending purposes. I would say your car is worth $40,000 to $41,000 retail. Unless you are in a tight market area, you will be lucky to get $41M.
I know this won't make you happy, but it is an honest appraisal.
A former dealer