Saying this for your own good. You are probably going to get destroyed in the finance office if you say stuff like “I want to negotiate to 53% RV”
Nobody smells blood in the water like a lethal F&I manager
The best place to get started is:
Please read links in there such as “how to calculate payments” and other helpful articles.
It might seem like a lot but TBH there are fewer <60 minute exercises which will save you so much time, money and anxiety over your driving lifetime.
It may also save you (after your negotiations with LH input) inside the finance office where no one can from the internet can really help you.
Remember, it’s almost impossible to reverse-engineer the math starting from the output (monthly payment) and figure out if it’s a good deal. Start at the beginning.