Pretty sure you'd be a dead man. Let's break this up shall we?
So if you're running @ 5 m/s at a distance of 100m, then it'll take you 20 seconds to get to the car. This is because distance/velocity=time. ••••• Now the Alligator is another story. He has to run 20m+100m and he runs @ 8 m/s. Using the same equation again, d/v= time, you will find that it takes the alligator 15 seconds to get to your car. So if it takes 20 secs for you to get to safety, and 15 secs for the alligator to maul you, if say you would die.