Depends on the corner.

I believe there was an episode of 5th Gear that took a Ducati 999 and Lamborghini Murcielargo around a track. The difference between the bike and the car was only 0.4 of a second (bike won though).

It also depends on the type of corner.....

TWISTIES: Usually the bike with a good rider will be faster than a good driver in a decently powered sports car. (though, usually any noob behind the wheel of a sports car can keep up with the bike). The rider would usually have to be experienced and skilled to beat the car though.

90 DEGREE CORNERS: Car will usually take this one at a much higher speed than the bike. (but the bike would be right on his ***).

HAIRPINS: Again, the car is usually faster. The car can brake later, and even brake through the turn. Bikes have to brake earlier, and then maintain traction throughout the turn. If the car breaks loose, it fishtails and that's pretty fun. If the bike breaks loose..........well.........that's not fun.

But whatever ground the bike looses through tight corners, it gains with outright speed.

 

it depends on the vehicle, skill of operator and conditions/type of road.