Two significantly similar cars, no doubt about that. Still, each one has something different to offer. Having both cars powered by petrol engines and utilizing the 2-door cabriolet body style within the same 'Sports car' segment, the only major difference here really is their wheel drive configuration (4 x 4 for the Porsche and rear in the case of the BMW). The first one has a Porsche-engineered powertrain under the hood, a 6-cylinder, 24-valves 480hp unit, while the other one gets its power and torque from a 6-cylinder, 24-valves 343hp engine designed by BMW.

The fact that the BMW got tested by the European New Car Assessment Programme (Euro NCAP), while the other contender didn't, offers a slight advantage, as the 4-star rating is better than none. Still, apart from the official crash test results there are other things we need to be aware of. Both vehicles belong to the sports car segment, which is generally classifying them somewhere in the middle safety-wise, but it doesn't do much to help us decide between the two. Furthermore, when it comes to weight, a factor that most people underestimate, 911 offers a considerable difference of 17% more metal.

Reliability is not the best thing to consider on the make level, but it is worth mentioning that BMW does have a slight advantage, when all the models are taken into account. That's the official data, while our visitors describe reliability of Porsche with an average rating of 4.0, and models under the BMW badge with 4.1 out of 5. Unfortunatelly, I don't have enough insight that would allow me to comment in more details on the specific models level. Above it all, drivers of cars with the same engine as 911 rank it on average as 3.0 out of 5, exactly the same as the other one.

Porsche is undoubtly more agile, reaching 100km/h in 1 seconds less than its competitor. In addition to that it accelerates all the way to 310 kilometers per hour, 60km/h more than the other car. When it comes to fuel economy the winner has to be BMW Z4, averaging around 12.1 liters of fuel per 100 kilometers (23 mpg), in combined cycle. We can't ignore that 7% difference compared to 911.

BMW appears just a bit more reliable, although the difference is truly marginal. The most important thing when deciding between any two vehicles should always be safety, both passive and active. In my opinion, everything taken into account, BMW Z4 offers significantly better overall protection, taking the lead here. From there things take a different direction, with Porsche outracing its opponent in any situation possible, making it better choice for boy racers. It does come at a cost though, and that's the fuel consumption... It's really tough to make a final decision here, but if I'd need to, I'd say BMW. Nevertheless, let's not forget that people have different preferences and needs, so what really counts is your personal feel. I'm only here to help. Also, you could use the oportunity to find out which car, everything taken into account, would be the perfect choice for you in the eyes of the virtual adviser™, among thousands of similar, yet so different vehicles.