I've read (I can't site the source) that your vehicle monthly payment shouldn’t exceed 20% of your monthly take home pay (after taxes)
So if this theory holds true it would mean for example:
Your take home pay is:
$2,500.00 = $500.00 car payment – You make approximately 40k a yr
$3,000.00 = $600.00 car payment – You make approximately 45k a yr
$3,500.00 = $700.00 car payment - You make approximately 50k a yr
And so on...
*For every extra 5k per yr you make you can afford and extra $100.00 in a car payment. This sounds about right to me but will not always hold true for everyone because not everyone has the same priorities, etc. Also, then again if you make say $2,500.00 but you live at home with Mom and Dad and don’t have to pay rent you can obviously afford something a little more, etc.