Two significantly similar cars, no doubt about that. Still, each one has something different to offer. Having both cars powered by diesel engines and utilizing the 4-door sedan body style within the same 'Luxury car' segment, the only major difference here really is their wheel drive configuration (rear for the BMW and 4 x 4 in the case of the Audi). The first one has a BMW-engineered powertrain under the hood, a 6-cylinder, 24-valves 265hp unit, while the other one gets its power and torque from a 6-cylinder, 24-valves 286hp engine designed by Audi.

Both vehicles got tested by European New Car Assessment Programme (Euro NCAP), with the same number of safety stars gained in the process. That aside, let's consider some other aspects which affect safety. Both vehicles belong to the luxury car segment, which is generally a very good thing safety-wise, but it doesn't do much to help us decide between the two. On the other hand, when it comes to weight, a factor that most people underestimate, Audi A6 offers a considerable difference of 11% 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, all the models observed together. These are the official statistics, while our visitors describe reliability of BMW with an average rating of 4.1, and models under the Audi badge with 4.2 out of 5. Independent research findings rank 5 Series as average reliability-wise, and A6 is more or less at the same level.Above it all, drivers of cars with the same engine as 5 Series rank it on average as 3.0 out of 5, exactly the same as the other one.

Audi is a bit more agile, reaching 100km/h in 0.2 seconds less than its competitor. In addition to that it accelerates all the way to 250 kilometers per hour, exactly the same as the other car does. When it comes to fuel economy the winner has to be 5 Series, averaging around 4.5 liters of fuel per 100 kilometers (63 mpg), in combined cycle. We can't ignore that 22% difference compared to Audi A6.

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, Audi A6 offers significantly better overall protection, taking the lead here. It all continues in the same direction, with Audi offering somewhat better performance, just enough to call it quicker. It does come at a cost though, and that's the fuel consumption... It's really tough to make a final decision here, but if I'd need to, I'd say BMW. 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. 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™, out of 12.000+ vehicles we currently have in our database.