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 small family car segment and utilize the same 5-door hatchback body style and the front wheel drive system, it all comes up to the specific diesel engine choice they offer. The first one has a Mazda-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 170hp 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. That aside, let's consider some other aspects which affect safety. Both vehicles belong to the small family car segment, which is generally classifying them somewhere in the middle safety-wise, but that fact doesn't break the tie between the two cars. On the other hand, taking kerb weight as an important factor into account, Q30 offers a considerable difference of 12% more metal.

I don't like generalizing things when it comes to reliability, although it does seem that Mazda does have a slight advantage, when all the models are taken into account. That's the official data, while our visitors describe reliability of Mazda with an average rating of 4.4, and models under the Infiniti badge with 4.5 out of 5. Unfortunatelly, I don't have enough insight that would allow me to comment in more details on the specific models level. That apart, owners of different cars powered by the same engine as Mazda 3 rank it on average as 5.0, while the one under the competitor's bonnet gets 4.5 out of 5.

Mazda is a bit more agile, reaching 100km/h in 0.2 seconds less than its competitor. Still, it lacks the power to win the top speed competition, topping at 210 kilometers per hour, 10km/h less than the other car. When it comes to fuel economy things look pretty much the same for both cars, averaging around 4.2 liters of fuel per 100 kilometers (68 mpg), in combined cycle.

Mazda 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, Q30 offers significantly better overall protection, taking the lead here. From there things take a different direction, with Mazda offering somewhat better performance, just enough to call it quicker. To make things even better, it consumps less fuel! No mistake, whatever you decide here, but I'd still go for the Mazda. 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. 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 more than 12.000 different ones in our database.