my dream car
There are so many factors that go into this I'll last just a few for you. You can pay MSRP and buy it for one payment. That's your your highest payment. You can negotiate the price and take a 72 or 84 month payment option. Your credit score. You can pretty much make your own monthly payment. You can put down a huge down payment and that will lower your payment. The more down the lower the less you pay monthly. There leading which is a whole different duck. If you need more help let me know. I do have a concern though. Your question leads me to believe you have never bought a car. I would strongly recommend you learn more about the process because if you don't, you'll be driving that A3 in your underwear as you will be taken to the cleaners.
Your credit score will have an effect as well. Leasing is a whole different duck. I added this because I didn't type this correctly above.
Search Audi A3 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Audi A3 Experts