New car tax in CA, how does this work?

I am selling my older car via newpaper for $10K and will buy a new car from a dealer for $30K in CA. I have the following questions.





1) Do I pay dealer the car taxes directly or do I pay to the city when I get my new tags?





2)Do I pay taxes for the entire $30K purchase? Or since I sold old car at $10K and buying new car at $30K, I should pay government the taxes on the difference of $20K, correct?





3)What is the CA car tax rate? Is it same as retail store tax rate around 8%?New car tax in CA, how does this work?
1) You pay sales tax at the dealership


2) You pay sales tax on the $30K (the car you're selling has nothing to do with this transaction)


3) CA has a STATE car sales tax rate of 7.25%