We can state with a great degree of certainty that the BMW M5 (F90) it's not exactly a slow car. When you have 600 hp under the foot, distributed over the four wheels, not even the more than 1900 kg of weight is an impediment to exceptional performances.
But apparently, it seems that the BMW M5 hides some tricks to get its fantastic performances. IND Distribution put an M5 on the power bank, and surprise: this one registered about 625 hp (634 hp)… but at the wheels.
Theoretically, this means that the V8 develops not 600 hp, but about 700 hp of power!
How is it possible to have more than 100 hp?
When looking at an engine's specs, the declared horsepower value is what is recorded on the crankshaft. However, the power that actually reaches the wheels is always lower. This is because there are mechanical losses (dissipated power), that is, some horses “get lost on the way” when passing through the gearbox and transmission shaft before reaching the wheels.
Hence the surprise in the results of this BMW M5 on the power bank. In this type of tests, it is only possible to measure the power to the wheels, after which the real engine power value is calculated, starting from a predetermined value of dissipated power.
That is, the results of this test should have produced a number around 530-550 hp — the value of dissipated power varies from car to car, but, as a general rule, it ranges between 10-20%. But, contrary to expectations, this M5, standard, with just over 1900 km, had at the wheel even more horsepower than the official 600 hp.
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Is it really possible to have 100 hp more?
It is possible, but it will hardly be. There are many variables that influence the power of an engine. From the lubricants used to the air temperature. From what we found in the information from IND Distribution, it was a particularly cold morning at the place where the test was carried out, but this is not a justification for the results presented.
And then, of course, there's this big variable called the power bank. Depending on the make/model of the power bank, the same car can present different values. From what we've seen, the power bank used is known to yield more optimistic numbers than other power banks.
Anyway, this BMW M5 took the test several times, and demonstrating how the numbers vary, the value reached of 625 hp was the best achieved in three with the car in 5th gear, all-wheel drive and Sport Plus mode — the other two stayed at 606 and 611 hp.
A test was also carried out with only two drive wheels (the new M5 has a 2WD mode), in 6th gear and Sport Plus mode, and the result was 593 hp to the wheels (whp).
Discrepancies… official
Finally, we also have to add another variable. The official numbers announced by the manufacturers do not guarantee that they are actually the real numbers debited by your car engine.
There are always discrepancies, especially in the turbo era we live in — two equal engines can present different power values below or above the official values, but in general, the differences are not expressive.
As we've already mentioned, there are many variables that affect the power of an engine. This is a jumble of parts, many of them mobile, and despite the rigors of industrial production today, tolerances do exist—no two parts are ever truly alike—affecting the numbers you get.
It's one of the reasons why manufacturers even tend to be conservative in the numbers announced , not only for its engines, but even for the performance of its machines, an even more sensitive issue when it comes to high-performance proposals.
It is necessary to ensure that all units reach the official numbers, so it is better to “level it out” — which also justifies some fantastic results for some machines in the performance achieved in some tests, better than the official numbers.
It always gives good publicity and avoids legal complications — in the past there have been lawsuits against some brands, because some of their models failed to reach the power they advertised.
And the BMW M5?
Suspicions that the M5's twin-turbo V8 is healthier than it appears, came from the previous generation (F10). As we are talking about a high base power, even a 5% discrepancy represents a gain of around 30 hp , which has been the norm of what has been measured in various power banks.
In this particular case, this engine is either “super healthy”, with super-tight tolerances, thus increasing the discrepancy to official values, which together with the optimistic power bank helped to these fantastic results; or else a calibration problem may have occurred. We will certainly see more tests of the BMW M5 on other power banks that could confirm or discredit this figure.
note: thank you to our reader Manuel Duarte for sending the information. We hope we have answered your questions.