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 4-door sedan body style and the 4 x 4 wheel drive system, it all comes up to the specific diesel engine choice they offer. The first one has a Volkswagen-engineered powertrain under the hood, a 4-cylinder, 16-valves 170hp unit, while the other one gets its power and torque from a 4-cylinder, 16-valves 177hp engine designed by BMW.

A starting point here would be to take a look at the results from European New Car Assessment Programme (Euro NCAP) tests which were performed on both of the cars, 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 large family car segment, which is generally a good thing safety-wise, still it doesn't help us solve our dilemma, does it? Furthermore, if we'd like to consider vehicle mass in this context too, which we definitely should, Audi A4 offers a marginal difference of 4% 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, at least on all of the models level. These are the official statistics, while our visitors describe reliability of Audi with an average rating of 4.2, and models under the BMW badge with 4.1 out of 5. The same official information place A4 as average reliability-wise, and 3 Series is more or less at the same level.Above it all, drivers of cars with the same engine as Audi A4 rank it on average as 4.2, while the one under the competitor's bonnet gets 3.7 out of 5.

BMW is a bit more agile, reaching 100km/h in 0.1 seconds less than its competitor. Still, it lacks the power to win the top speed competition, topping at 224 kilometers per hour, 4km/h less than the other car. When it comes to fuel economy things look pretty much the same for both cars, averaging around 5.6 liters of fuel per 100 kilometers (51 mpg), in combined cycle.

Audi 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 A4 offers slightly better overall protection and takes the lead. When it comes to performance, both vehicles provide similar experience, so I wouldn't point any of them out. 3 Series still consumps less fuel, which needs to be taken into consideration. At the end, as much as I'd like to give you a winner here, it's simply a pure tie if you ask me. Anyway, that's the most objective conclusion I could've came up with and it's based solely on the information found on this website. Aspects such as design, practicality, brand value and driving experience are there for you to measure them out. 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™, among thousands of similar, yet so different vehicles.