Another reason for choosing a car seat is comfort, yes, you can use dog seat belts. (dogsbarn.com)
A homemade dog seat for the car keeps your dog safer and happier during trips and outings. (smartdogowners.com)
Besides using a portable dog crate or pet carrier there are also dog seat belt harness systems and vehicle pet barriers that will make the car travel safer for everyone. (dog-supplies-advisor.com)