Financing with right of return, monthly rates increase meaningfully?

Hello, I’m new here and I need your help I paid for my first car from the saved car, so I have no idea of financing, but I’ve already informed myself everywhere. I want to finance an Audi A4 car with VarioCredit. As a down payment my old car should be used. The loan amount would be about 30k€, I want to finance for 48 months with 15000 km/year. If I use the proposed rates of the Audi online computer I would have to use about 330€ This would be the value of the car with a certificated right of return ?! Now the dealer asked me how much I would like to pay monthly. I said 400-450€ to keep the final rate lower and because I could pay so much monthly. Now the question: What good is the certificated right of return now ? The final rate (about 13k€) is then lower than the value of the car. If I would then return the car in 4 years, b or would you recommend to keep the monthly rates as low as possible and to put away something in private every month? Thank you very much.