Well, these are two pretty similar cars we have here! It's only details that could potentially make the difference. Considering they both belong to the sports car segment and utilize the same 2-door cabriolet body style and the rear wheel drive system, it all comes up to the specific petrol engine choice they offer. The first one has a BMW-engineered powertrain under the hood, a 4-cylinder, 16-valves 156hp unit, while the other one gets its power and torque from a 6-cylinder, 24-valves 265hp engine designed by Porsche.

Unfortunatelly, neither of the two vehicles was submitted to the European New Car Assessment Programme (Euro NCAP) testing. This makes it virtually impossible for me to pick one over the other and I'm generally against buying such cars as the safety should really always come first. 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, taking kerb weight as an important factor into account, BMW Z4 offers a marginal difference of 3% 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, all the models observed together. These are the results of an independent reasearch, while our visitors describe reliability of BMW with an average rating of 4.2, and models under the Porsche badge with 3.7 out of 5. Unfortunatelly, I don't have enough insight that would allow me to comment in more details on the specific models level. That apart, owners of different cars powered by the same engine as BMW Z4 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 2.1 seconds less than its competitor. In addition to that it accelerates all the way to 264 kilometers per hour, 43km/h more than the other car. When it comes to fuel economy the winner has to be BMW Z4, averaging around 6.8 liters of fuel per 100 kilometers (42 mpg), in combined cycle. We can't ignore that 24% difference compared to Boxster.

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 slightly better overall protection and takes the lead. From there things take a different direction, with Porsche being considerably quicker, thus putting more smile on driver's face. It does come at a cost though, and that's the fuel consumption... I believe that, when we take all into account, we have only one winner here - the 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. In case you have two minutes to spare I invite you to define your needs, desires and budget and see which car would be chosen by the virtual adviser™, among thousands of similar, yet so different vehicles.