I've used that 12 V dustbuster I initially linked to for a while now and have some reports. The only thing it didn't come with is a long and narrow suction tube to get down in deeper crevices. As delivered with the flexible hose and long snout, it works great to get up at least 90% of the dirt that would be on a car floor. The wider nap that makes up cheaper car carpets might hold sand and dust down deeper, and if you lived in areas that primarily had brown silt type ultrafine clay soil, I can't say whether it would suck every last bit.
But it really does have good suction and is super easy to clean. It really works great for the sand and soil kind of dirt that typically ends up on my carpet. It was a bit pricier to buy, but I think it was worth it because it really works well. It packages up nicely into a small bag it is supplied with, and it has more than a long enough cord to reach where you need.
The downsides are very few. Primarily just a lack of a long crevice type tool which is always a necessity in automotive vacuuming scenario, and the fact, which was my fault, but because the cord is so long, I accidentally dropped the lighter plug end onto the pavement and it fractured the tip. Works just fine and a little bit of crazy glue fixed it right up, for something that will be dropped I would have thought it would be a bit more compliant. The only other issue which is merely physics, is that the metal conductors on the cigarette lighter end, get really hot under operation. In roughly 10 minutes that it takes to do both front positions, the metal conductors get hot enough that you cannot touch them without burning yourself. I believe the vacuum pulls around 12 A, and who knows what corrosion is in my 20-year-old socket.
Overall though I highly recommend this. Only time will tell how well it lasts, and they do recommend to not operate with the car running, so the voltage that the vacuum is fed is obviously an issue. I'd say that in 10 to 15 minutes worth of vacuuming that I performed, my battery went from 12.72 to 12.45V, under load, and then recovered to around 12.65V. So practically speaking I say you lose about 10% battery state of charge for every 15 minutes of use.
It's a good little machine and again I recommend it.
