except the bugatti which transfers the whole lot down, fastest road car right now, me want

The only way that would be possible would be if they only measured the cars power at the wheels. I personally think this would be better anyway because the power at the wheels is all you can use. Remember, a car is a machine and therefore cannot be perfect. There will be a percentage of power lost between the flywheel and the ground, its just a fact of simple physics.
However, if the "advertised" horsepower was the power measured at the wheels-then yes you could say that all the power was transfered to the ground.
I would imagine the Bugatti (not knowning anything about it) probably had its horsepower measured at the flywheel because that way you get the absolutely highest number of horsepower possible for advertising. Then, they concentrated on building a really efficient drive train to minimize the power lost. Could a Skyline (or a Camaro...or any car for that matter) be as efficient? Sure, its possible with enough money. Is it worth it...probably not.