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 355hp 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. That aside, let's consider some other aspects which affect safety. 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, 911 offers a considerable difference of 12% more metal.

I don't like generalizing things when it comes to reliability, although it does seem that BMW does have a slight advantage, when all the models are taken into account. These are the results of an independent reasearch, while our visitors describe reliability of Porsche with an average rating of 3.9, 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 a bit more agile, reaching 100km/h in 0.1 seconds less than its competitor. In addition to that it accelerates all the way to 293 kilometers per hour, 43km/h more than the other car. When it comes to fuel economy things look pretty much the same for both cars, averaging around 11.8 liters of fuel per 100 kilometers (24 mpg), in combined cycle.

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. To make things even better, it consumps less fuel! It's not difficult to say then that if I'd need to make a choice, it would definitely be the Porsche. Anyway, that's the most objective conclusion I could've came up with and it's based solely on the information found on this website. Aspects such as design, practicality, brand value and driving experience are there for you to measure them out. 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.