[Dominik]

The old "conversion" from rwhp to engine looked sort of like this:
496hp at the rear wheels (80%) due to 20% losses in the drivetrain (that's a lot of heat in your drivetrain, mate! About 85 hair dryers) from "620hp" at the flywheel.

The real losses are more like 10% in direct (4th) gear. Hot rodders now like to add another 80hp for poor exhaust flow and accessories.

Now you have 700hp!

Why would one add losses from exhaust or accessories? What you have at the flywheel is what you have. And some exhausts are very efficient.

It's more like this:
496hp rwhp equals to 555hp at the flywheel. Not 700hp (like 555hp isn't enough!)

There is another flaw, quite minor in this overall picture, DIN and SAE readings. DIN is done at 70F, SAE at 60F.

(Above numbers were actual readings from my car's coast down/acceleration test in 1995 with a GM computer attached on a raod with known profile)