First off, let me just warn everyone here, Lego's cheating a little bit. But, seeing as how the race is so unbalanced to begin with, that's probably okay. And, in the end, there's sort of a physics lesson to be learned, so I guess we're all winners.
If the video doesn't work for you, try watching it here.
Now, I'm actually not totally certain about the physics lesson being given here. The host suggests the Lego car was able to out-accelerate the rolling 911 because of its less mass, but, as astronaut David Scott showed us on the moon, mass is not a factor for gravitational acceleration:
If I had to guess, I'd say the Lego car was able to out-accellerate the Porsche because of less mechanical rolling resistance and air resistance, due to its much smaller frontal area. Maybe I'm wrong? Any physics-types want to chime in?