I have seen car Vaccum Cleaner Which can be connected to the car lighter plug,but they are not powerful enough i think.Anyway if you are interested i will let you know more about it.
I got one "Eureka Forbes Easy Clean Vacuum Cleaner" free on some year-end offer.
Its not actually a car vacuum cleaner, but small and handy so i can use it to clean car carpets and seats. It needs power though, no battery support.
Looks good. I am sure it does the job well since its a eureka forbes product. I use the one which is connected to the lighter plug for power and it does the cleaning quite well.
Eureka forbes' product is no doubt the best one but you can checkout this page on Ebay.I hope you get one useful and efficient vacuum cleaner at a cheaper cost.Hope it helps you.