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 sports car segment and utilize the same 2-door cabriolet body style and the rear wheel drive system, it all comes up to the specific petrol engine choice they offer. The first one has a Opel-engineered powertrain under the hood, a 4-cylinder, 16-valves 147hp unit, while the other one gets its power and torque from a 6-cylinder, 24-valves 170hp engine designed by BMW.

The fact that the BMW got tested by the European New Car Assessment Programme (Euro NCAP), while the other contender didn't, offers a slight advantage, as the 4-star rating is better than none. Still, apart from the official crash test results there are other things we need to be aware of. Both vehicles belong to the sports car segment, which is generally classifying them somewhere in the middle 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, BMW Z4 offers a potentially life-saving difference of 44% more metal.

Manufacturers have been building their reliability reputation for decades now and, generally speaking, it appears that Opel does have a slight advantage, when all the models are taken into account. These are the results of an independent reasearch, while our visitors describe reliability of Opel, as well as BMW, with the same average rating of 4.2 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 Speedster rank it on average as 4.2, while the one under the competitor's bonnet gets 4.4 out of 5.

Opel is undoubtly more agile, reaching 100km/h in 1.8 seconds less than its competitor. Still, it lacks the power to win the top speed competition, topping at 217 kilometers per hour, 8km/h less than the other car. When it comes to fuel economy things look pretty much the same for both cars, averaging around 8.7 liters of fuel per 100 kilometers (33 mpg), in combined cycle.

Opel 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, BMW Z4 beats the other contender by far, making it the best choice without even considering other things. From there things take a different direction, with Opel being considerably quicker, thus putting more smile on driver's face. To make things even better, it consumps less fuel! I believe that, when we take all into account, we have only one winner here - the BMW. 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. 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™, among thousands of similar, yet so different vehicles.