We're not eBay. We're just other users like yourself, and can't help you with eBay's charges. Listing fees for motor vehicles are not refundable if the vehicle doesn't sell. I take it that you have cancelled any sales in which a buyer bought the item, but didn't pay? Otherwise eBay may hold you liable to pay the full final value fee(s).

Go to eBay's fees page fo private sellers and take a look at the fees for selling a car as a classified ad. The are much lower and most importantly the ad isn't taken down when a buyer offers the price, only when you take it down yourself after the sale has been completed.