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 Porsche-engineered powertrain under the hood, a 6-cylinder, 24-valves 240hp unit, while the other one gets its power and torque from a 6-cylinder, 24-valves 218hp 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, taking kerb weight as an important factor into account, Boxster offers a marginal difference of 3% more metal.

Manufacturers have been building their reliability reputation for decades now and, generally speaking, it appears that BMW does have a slight advantage, all the models observed together. 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. The same official information place Boxster 50% below average, and Z4 those same 50% above the first one. Above it all, drivers of cars with the same engine as Boxster rank it on average as 3.0, while the one under the competitor's bonnet gets 4.2 out of 5.

Porsche is a bit more agile, reaching 100km/h in 0.3 seconds less than its competitor. In addition to that it accelerates all the way to 256 kilometers per hour, 16km/h more than the other car. When it comes to fuel economy the winner has to be BMW Z4, averaging around 8.4 liters of fuel per 100 kilometers (34 mpg), in combined cycle. We can't ignore that 14% 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 much better overall protection, which launches it ahead of the other contender. 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... All together, there's not much more to say, in this case I wouldn't even consider anything but 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™, out of 12.000+ vehicles we currently have in our database.