1. The plural on car is a killer for this name. There are times when the first word can be pluralized and have the name sound maybe a bit unnatural but still reasonable (like with a past tense verb used as adjective, ex. CarsFeatured.com or an adjective sometimes like CarsNew.com or CarsElite.com). This is not one of those times though.
2. Car and bid are not searched together as much as you might have thought. Only 309 for "car bid" on OST, which covers both as singular, both as plural, and singular plural, plural singular. That's not a very high number at all, so a name like this that's somewhat bottom of the barrel compared to other car bid domain names still shares some of the pie, but the pie isn't that big to begin with.
I would have to say reg fees to maybe $12 or so. You may get lucky and find someone that likes the name more than that, but I doubt it. Good luck!