The analogy between automobiles and software testing can be extended to consider the racing line - the combination of velocity and distance through a corner which results in the fastest time.
Which brings me to the point that the steering wheel is much more important than brakes. Being able to go faster because of brakes is not very useful if you are heading into a wall.
Well, you can still stop before hitting that wall. Steering might be of little use if you're going fast and approaching a dead end with walls on either side.
Perhaps we've driven beyond the metaphor.
We're on the verge of realizing trail braking and heel toe in software development!