My question revolves around the car business. If some of my income is derived from collecting interest, is this considered haram income? Let me give you details: Customer comes to the car dealership to buy a car, requires financing, we contact the bank and the bank gives us an approval interest rate, the dealership in turn marks up that approval rate and profits the difference. My paycheck is derived from getting a percentage of that difference. Is this haram income because the source is from interest?

My question revolves:
If you are 100% sure that your paycheck contains such part, then it is haram, and you have to pay it back to the customer, and if you do not know him, then you have to give it as sadaqa on his behalf (if he is Muslim).
But, if you are not sure, but you suspect that part of your paycheck is from that income, then you are in the safe side.