Recently BMW has made a commitment to turbocharging their entire lineup in the name of efficiency. Many enthusiasts are skeptical that this move will serve to improve the cars, but I think otherwise. I have driven a few 335is and can say that BMW has gotten these boosted cars to deliver their power very smoothly. They are a far cry from the more crude turbocharged cars of old that were plagued by excessive lag and sudden onset power that could unset the car’s balance in a corner. These cars seem to be living up to the BMW reputation quite nicely, and have even shown some surprises that BMW executive wanted to conceal on paper in order to preserve demand for their other cars.    

There are three different examples where I have noticed BMW’s obvious underrating of the power of their new engines. Readings by media and customers on chassis dynos that measure power at the wheels suggest that BMW has significantly underrated the output of their engines on paper. The first up is the new Z4 sDrive28i, it replaced the naturally aspirated 3.0L inline 6 with a turbocharged 2.0L inline 4 cylinder. On paper the new four banger makes 240bhp and 260 ft/lbs of torque but on a chassis dyno it put down 233whp and 249wtq. Factoring in around 15% drive train loss for a rear wheel drive car and actual output of the 2.0L motor is around 274bhp. With a curb weight of 3200-3300lbs, this base model Z4 will be able to compete with the likes of the Lotus Elise, Subaru STI, Mitsubishi Evo, and Nissan 370Z in speed, not bad for the entry level model.

The second one is the new 1 Series M. This car puts out around 340bhp on paper but actually winds up making around that much power at the rear wheels when tested. This means the 1M is actually makes more like 390bhp which would put it hot on the heels of the legendary M3. This all makes sense considering how the 1M has been upsetting the M3 in most comparison tests around the world. Mix all of this with the potential for serious gains off of basic modifications and you will see why BMW chose to underrate it’s power figure on paper; there would be no reason to buy an M3.

(Owner’s dyno results here)

Lastly there is the BMW F10 550i. BMW states 400hp for this top of the line 5 series, but when put on the dyno, customers have seen ~385whp from it. This suggest that the motor is actually putting out more like 450bhp which is quite a bit more than 400 if you ask me.

I understand why BMW, and other companies, choose to underrate their cars on some occasions; it is necessary to keep their own models from competing with one another. There really is not any harm done either because the customer is just getting more for their money. The point of all this was to bring this practice of underrating cars on paper to light in order to give our readers a more realistic view of the industry. BMW has been making some serious cars and I wholeheartedly support their switch to boosted engines. So far all is well and I cannot wait to find out if the new M5 is underrated as well because I hope that it is making more like 600hp as to differentiate itself a bit from that ghastly X6M. BMW, please keep up the good work.

-Nick