TomO said:
why? because manufacturers all do the test in the same way? (peugeot often quote figures based on 2 adults and luggage in the car)
and other manufacturers are
never optismistic?
Peugeot specifically state how they quote their figures and always have, many people just chose to ignore the small print!
On the whole, manufacturer's are pretty good at getting quite accurate results. Far more accurate than simply punching just
two figures in to a "one-size-fits-all" calculator such as the one on LetsTorqueBHP and hoping for the best. It does, for example, does not take torque in to account at all. A common rail diesel unit with 150hp is the same as a petrol unit with 150hp according to that thing - which just isn't true. In fact, I will go the extent of saying that the calculator is completely pointless for generating actual performance statistics. It's only useful purpose is to have a human manually adjust the figures until the performance matches manufacturer spec, and then calculate
roughly the performance gains from power modifications.