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 luxury car segment and utilize the same 4-door sedan body style and the rear wheel drive system, it all comes up to the specific diesel engine choice they offer. The first one has a BMW-engineered powertrain under the hood, a 6-cylinder, 24-valves 313hp unit, while the other one gets its power and torque from a 6-cylinder, 24-valves 265hp engine designed by Mercedes Benz.

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. Moving further on, let's take a closer look at some additional safety-related facts. Both vehicles belong to the luxury car segment, which is generally a very good thing safety-wise, but that fact doesn't break the tie between the two cars. Furthermore, taking kerb weight as an important factor into account, 6 Series Gran Coupe 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 both brands display similar results in faults and breakdowns, all the models observed together. That's the official data, while our visitors describe reliability of BMW with an average rating of 4.2, and models under the Mercedes Benz badge with 4.4 out of 5. Independent research findings rank 6 Series Gran Coupe as average reliability-wise, and CLS is more or less at the same level.That apart, owners of different cars powered by the same engine as 6 Series Gran Coupe rank it on average as 4.6, while the one under the competitor's bonnet gets 4.8 out of 5.

BMW is a bit more agile, reaching 100km/h in 0.8 seconds less than its competitor. Still, it lacks the power to win the top speed competition, topping at 250 kilometers per hour, exactly the same as the other car does. When it comes to fuel economy things look pretty much the same for both cars, averaging around 5.8 liters of fuel per 100 kilometers (49 mpg), in combined cycle.

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, 6 Series Gran Coupe offers slightly better overall protection and takes the lead. It all continues in the same direction, with BMW offering somewhat better performance, just enough to call it quicker. 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 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 more than 12.000 different ones in our database.