Sliding the deer under your car is also really bad for you. It's going to do a lot of damage under there such as ripping break lines, destroying ball joints, or fragging your differentials. You need to safely shed as much speed as possible while maintaining your lane when about to hit a deer.

A moving vehicle in real life is a bit more complicated of an equation, factor in the car's angle towards the horizontal as you accelerate or brake, that's the original point, but whatever.