1 Speed Racer would never stoop to using weapons against a fellow race-car driver!  As I recall, Speed used those for cutting down trees when he raced through a forest.  Of course, high-speed tree-felling raises other engineering problems...

2 I have great doubts that it could get close enough to a F1 car to use them, let alone have the blades get pushed vertically.  As wonderful as it is, the Mark 5 just wouldn't be fast enough to keep up. 

However, I could see it being raced in Sports Car marques, like the various endurance championships or even just straight GT racing.  I'll ignore that it really isn't a GT at all, but a straight-up Prototype; probably a LMP2 or whatever that class is called nowadays.

3 You'd use it on their fairings as they lapped you, and then goodbye fancy aerodynamics, and maybe structural integrity, too.

4 Fairings, huh?  Ooookayyyyyyy....