You don't need to buy specialized cleaners. You can easily clean the car interior, using household detergents and goods, so do it as often as possible!
1.Vacuum & Wipe
Remove floor mats and vacuum the car interior.
Remove sand, dust, hair, food debris, etc.
Be sure to clean narrow areas such as between sheets where tiny dust tends to pile up.
Wipe using a diluted laundry detergent.
Pour a moderate amount of the laundry detergent into a bucket and dilute it by about 100 times with water. Wet a towel with the diluted laundry detergent, wring it tightly and wipe the car interior. You will see that steering wheels, dashboards, seats and other places are dirtier than you expect.
2.Clean Car Floor Mats
Dust & Vacuum.
Dust floor mats using a carpet beater in order to remove sand and mud, and vacuum.
Use a fabric softener to keep the floor mats soft.
The fluffy mats tend to become rough after washing with detergent and drying. Use a fabric softener! Pour a moderate amount of the fabric softener into a bucket, dilute it by about 50 times with water and wash the mats with the diluted liquid instead of detergents. Rinse thoroughly, dry and you're done! The mats will be clean and soft!
Depending on the materials, some mats can't be washed. Ask your car dealer for more information.
A tip on drying the mats quickly: Dry by Hanging the Mats Diagonally!
Dry the mat in the shade, hanging with the corners pointing down. This allows the mat to dry quickly, because water comes to the corner and drips out efficiently. If you dry the mat hanging it straight up, it takes much more time than you expect.
If you place the wet mat in the car, it may cause mold and odors.