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 4-door sedan body style within the same 'Executive 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 Audi). The first one has a Mercedes Benz-engineered powertrain under the hood, a 8-cylinder, 32-valves 388hp unit, while the other one gets its power and torque from a 12-cylinder, 48-valves 500hp engine designed by Volkswagen.

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. Still, apart from the official crash test results there are other things we need to be aware of. Both vehicles belong to the executive car segment, which is generally a fortune safety-wise, but that fact doesn't break the tie between the two cars. On the other hand, if we'd like to consider vehicle mass in this context too, which we definitely should, Audi A8 offers a marginal difference of 9% 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. These are the official statistics, while our visitors describe reliability of Mercedes Benz with an average rating of 4.4, and models under the Audi badge with 4.2 out of 5. Some independent research have also placed S as average reliability-wise, and A8 is more or less at the same level.Above it all, drivers of cars with the same engine as Mercedes Benz S rank it on average as 5.0 out of 5, exactly the same as the other one.

Audi is a bit more agile, reaching 100km/h in 0.7 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 Mercedes Benz S, averaging around 11 liters of fuel per 100 kilometers (26 mpg), in combined cycle. We can't ignore that 13% difference compared to Audi A8.

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, Audi A8 offers slightly better overall protection and takes the lead. 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... No mistake, whatever you decide here, but I'd still go for the Mercedes Benz. 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. I suggest you spend two more minutes in order to find out which car, based on your needs and budget, would be picked by the virtual adviser™, out of 12.000+ vehicles we currently have in our database.