Computers can run a car at the limits of its traction circle much better than humans can, even with nothing more than an accelerometer. I've done some hacking around this, and it turns out that you can go about it fairly naïvely, code-wise, and do way better than even good amateur racers. Unfortunately, I don't have access to any top F1 drivers to datalog them side by side with my software, but maybe someday.
In terms of the quickest path around a given course, computers are _way_ better than humans at that. There's the official "racing line", which is a generally accepted fastest line, but as you can create more acceleration, the line actually flattens out towards the shortest route through a given section. Take a look at something like Spec Miata vs an AWD time attack car for a great demonstration of this.
Humans still have the edge on understanding & interpreting the environment. There's a lot of work being done in this area, though - I suspect we'll get some fairly robust stuff that's available to us on the open market in a few years.
Then there's the fatigue factor.
Heck, if nothing else, having to cart around 150-180lbs of meat with fairly tall packaging and some weird requirements about having to see and what kind of forces you can exert on it is a bit of a drag to making the quickest possible wheeled vehicle.
Sorry for the wall of text - this is something I've been hacking around a bunch for the last while, as it's the intersection of a bunch of my interests. Drop me a line if you want to chat more about it sometime.