A quick spreadsheet shows that at 9% interest (which interest can vary wildly, depending on who's getting the car) if one follows the 20-4-10 rule (20% down, for no more than 4 years, no more than 10% of income for payments and insurance), for each $5,000 the car costs adds $100 to the monthly payment. A $20,000 car would be about $400 per month, for an example. That doesn't include taxes, fees, insurance or gas, which can vary wildly depending one many factors. But assuming it all works out to $100 per month (except fuel, maintenance and repairs which seem to be in addition to the 10% of the 20-4-10 rule) then for every $12,000 a person/household makes per year they can afford $5,000 more car or $100 per month. For an example, someone making $60,000 could afford no more than a $20,000 according to that rule, assuming their insurance and tags don't amount to more than $100 per month and their interest rate is 9%.
The Dave Ramsey rule is all vehicles shouldn't be worth more than 50% of total income, So a $60,000 earner can "afford" a $30,000 according to Ramsey. IIRC, Dave Ramsey also doesn't approve of getting an auto loan, so it's $30,000 max, but not more than what you have in cash. Which if that's $1,000 in cash, then you can only afford a $1,000 car.
Sam Dogen’s rule is only 1/10 of annual income?! (A $60,000 per year earner only can afford a $6,000 car!?, Who is this Sam Dogen?!)
https://walletbliss.com/how-much-car...0%20in%202019.