I think this vacuum cleaner is not doing any job cleaning car, or i don't know how to use it, guys share ur experience

Are you sure you have been using it right? Try to add a picture of the device.

The device works like magic sucks out all the dirt in my car I think you shud learn how to go about using it as its a life saver

Mine works like a charm.

My recommendation is to get a very powerful vac for the house like on cozzyand use that for the car. I've got an VonHaus. The powerful suction combined with a crevice tool will pull a lot of sand out of the carpet.
My cars have mats so the 'carpet' in the car pretty much just gets sand and bits of grass which somehow don't get caught in the mats. The real crud ends up on the mats and I give them the odd clean with my Hoover Gladiator carpet cleaner after a going over with the vac.