A comparison - Horse/Jockey Driver/Car

[2MinsToPost]

I can speak intelligently about Auto Racing and this comparison, but obviously not the former, Horse/Jockey. I'll use Nextel Cup as my example since most on here are familar with it. On a SuperSpeedway, say Daytona, Talladega etc the car setup is by most accounts 80-90% responsible for how well that car/team/driver perform on that day in that race. Now, on a short track, say Bristol (1/2 mile) the driver is by most accounts 30-40% of the equation where as the car setup is 60-70%. Drivers are the first ones to tell you this, the ones who know what they are talking about.

Now, what are the percentages in Horse Racing? A 1 1/16th Allowance or Stakes Race versus a 6 Furlong Allowance or Stakes?

I know from previous reading that Turf Races are different, so lets stick with dirt. I just wonder, watching a horse come down the stretch, when a Jockey is cracking the whip, how much difference that makes? Are some horses just "natural" fighters, competitive by nature and hate to lose? Are some horses just "natural" slackers? Does the jockey, on a slacker or fighter, make that much of a difference?