If you take home $4,000 a month, a realistic car budget usually starts with a monthly payment target, not the sticker price. For many buyers, a practical starting point is about $250 to $400 a month for the loan payment, with room left for insurance, fuel, maintenance, and registration. A good single number to use while shopping is about $350 a month for the payment and about $550 a month for total car-related spending. That does not fit every budget. Before you decide, subtract your fixed bills and savings goals from the $4,000, then see what is left for transportation without stretching the rest of your month.
Completion
You know the budget is working if the payment is about $350 or less, your total car-related spending stays near $550 a month, and you still have room in your budget for the rest of your life. That is the level to use when you start comparing cars.