Why does it use “if will”?

Question

From 2 Broke Girls:

I'm going to the prom with Brandon, if his dad will lend him the car.

Why does the quote use "if ... will"?

After reading this ELL question, I think it should be if ... would

Answer 1

"Will" does not always function as a future marker; it can be used to mean "be willing to." So your sentence amounts to "I'm going to the prom with Brandon, if his dad is willing to lend him the car."