First, it is difficult to say whether you can enjoy the 30% interest rate discount, because many banks have canceled or tightened the 30% interest rate discount. You need to ask ICBC for this specific information.
Second, there is no conflict between your loan to buy a car and your mortgage to buy a house. If you have bought a car with a loan from Standard Chartered Bank, you are considered a good customer to the bank to a certain extent. It just means that your monthly loan repayment pressure may be a bit high. Of course, if you have a good job, it is not a problem.