Uhm, think again, you fit the extinguisher in the trunk, near the engine, where the fire usually starts. How are you going to reach it when you engine is on fire?
i have practiced grabbing the unit and can grab it VERY fast. Notice HOW it is installed with the bits at easy reach.
Of course if you REALLY want to do it right, get a proper race system permanently installed with an activation button in the cockpit (and also one in the trunk). i debated doing that actually, but decided against it for now.