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 large family car segment and utilize the same 5-door wagon 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 4-cylinder, 16-valves 150hp unit, while the other one gets its power and torque from a 4-cylinder, 16-valves 143hp engine designed by Mercedes Benz.

The first thing to look into here would be the results from European New Car Assessment Programme (Euro NCAP) tests performed on the two cars. Good thing is that both vehicles got tested, with the same number of safety stars gained in the process. Still, apart from the official crash test results there are other things we need to be aware of. Both vehicles belong to the large family car segment, which is generally a good thing safety-wise, still it doesn't help us solve our dilemma, does it? Furthermore, when it comes to weight, a factor that most people underestimate, 3 Series offers a marginal difference of 1% more metal.

I don't like generalizing things when it comes to reliability, although it does seem that both brands display similar results in faults and breakdowns, when all the models are taken into account. That's the official data, while our visitors describe reliability of BMW with an average rating of 4.1, and models under the Mercedes Benz badge with 4.3 out of 5. Some independent research have also placed 3 Series as average reliability-wise, and C is more or less at the same level.Above it all, drivers of cars with the same engine as 3 Series rank it on average as 4.3, while the one under the competitor's bonnet gets 5.0 out of 5.

BMW is undoubtly more agile, reaching 100km/h in 1.4 seconds less than its competitor. Still, it lacks the power to win the top speed competition, topping at 211 kilometers per hour, 3km/h less than the other car. When it comes to fuel economy the winner has to be 3 Series, averaging around 5.7 liters of fuel per 100 kilometers (50 mpg), in combined cycle. We can't ignore that 18% difference compared to Mercedes Benz C.

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, 3 Series 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! 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™, among thousands of similar, yet so different vehicles.