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 Mercedes Benz-engineered powertrain under the hood, a 6-cylinder, 18-valves 218hp unit, while the other one gets its power and torque from a 4-cylinder, 16-valves 147hp engine designed by Opel.

The fact that the Mercedes Benz 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 that fact doesn't break the tie between the two cars. Furthermore, when it comes to weight, a factor that most people underestimate, SLK offers a self-explainatory difference of 50% more metal.

I don't like generalizing things when it comes to reliability, although it does seem that Opel 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 Mercedes Benz with an average rating of 4.3, and models under the Opel badge with 4.2 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 SLK rank it on average as 4.6, while the one under the competitor's bonnet gets 4.2 out of 5.

Opel is undoubtly more agile, reaching 100km/h in 1 seconds less than its competitor. Still, it lacks the power to win the top speed competition, topping at 217 kilometers per hour, 28km/h less than the other car. When it comes to fuel economy an obvious choice would be Speedster, averaging around 8.5 liters of fuel per 100 kilometers (33 mpg), in combined cycle. That's 31% difference compared to SLK!

Opel 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, SLK beats the other contender by far, making it the best choice without even considering other things. When it comes to performance, both vehicles provide similar experience, so I wouldn't point any of them out. Speedster is in a different dimension economy-wise, and many people will find that crucial. No mistake, whatever you decide here, but I'd still go for the Mercedes Benz. 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.