Do you have a vacuum at home just for your car, a shop vac etc? I've considered getting one to use, instead of going to the car wash, or using the house vacuum. I just don't know if it's worth it, just to use on the car.
I agree with Dodge Doll, if you have a dust-buster in addition to your vacuum, I don't really see the need. That's just what works for me though, I'm sure some people prefer something better.
I actually have a smaller like jet air vac that I keep in the house near the kitty box and its a perfect size to stretch across the back deck to vac out the vehicles here. Maybe twice a year I will go out and pay to have it professionally done but most times its just easier to take 10 minutes on the weekend.
We have a shop-vac. Since we have very little carpet in our house, it mostly gets used for blowing air, or for vacuuming the minor things (like the car) that need to be vacuumed.
Right now I just vacuum at the car wash. If I did it more often I think it would be great to have a shop vac at home. My house vacuum doesn't seem to do a great job, something more forceful would be better.