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 (rear for the Mercedes Benz and 4 x 4 in the case of the Porsche). The first one has a Mercedes Benz-engineered powertrain under the hood, a 8-cylinder, 32-valves 591hp unit, while the other one gets its power and torque from a 6-cylinder, 24-valves 520hp 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. 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 that fact doesn't break the tie between the two cars. On the other hand, taking kerb weight as an important factor into account, 911 offers a marginal difference of 2% more metal.

I don't like generalizing things when it comes to reliability, although it does seem that Mercedes Benz does have a slight advantage, at least on all of the models level. That's the official data, while our visitors describe reliability of Mercedes Benz with an average rating of 4.4, and models under the Porsche badge with 3.8 out of 5. The same official information place SLS as average reliability-wise, and 911 is more or less at the same level.That apart, owners of different cars powered by the same engine as SLS 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 0.2 seconds less than its competitor. Still, it lacks the power to win the top speed competition, topping at 315 kilometers per hour, 5km/h less than the other car. When it comes to fuel economy an obvious choice would be 911, averaging around 9.9 liters of fuel per 100 kilometers (29 mpg), in combined cycle. That's 33% difference compared to SLS!

Mercedes Benz 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, 911 offers slightly better overall protection and takes the lead. It all continues in the same direction, with Porsche offering somewhat better performance, just enough to call it quicker. To make things even better, it consumps less fuel! All together, there's not much more to say, in this case I wouldn't even consider anything but Porsche. In any case that's my personal view, built upon all the data available to me. What should decide here though is the way you feel about the two vehicles, and I hope you'll find my guidelines useful in the process. 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 more than 12.000 different ones in our database.