Whenever talking about the safety of a convertible, most people's self preservation instinct starts talking for them. Not to say that is wrong, or that we have a completely different opinion on the subject, but in general, things are not as grim as they appear. The BMW 1-Series Cabriolet is built on exactly the same platform as the 1-Series hatchback and shares more than a few technical bits with the current 3-Series sedan (E90). Both these related cars have a five-star rating at EuroNCAP and went through several crash tests with flying honors.
This, of course, doesn't mean that a convertible version should be just as protective to its occupants, especially considering the fact that the whole roof has been chopped off, therefore modifying the whole crash structure and the passengers cell with it. Still, like pretty much every convertible-maker out there, the 1-Series underbody structure has been stiffened for two highly logical reasons.
First of all, by chopping the body and leaving it with a foldable canvas roof, a car is more prone to bending forces. So, the underbody is stiffened in order for the car to handle at least as well as its coupe version. The other reason is, obviously, crash protection.
On top of this, our test car was fitted with four airbags, two dual-stage frontal ones and two for side impact protection and the regular anti-lock braking system and electronic stability program. But what would happen in the unfortunate event of a rollover, you might ask?
Well, first of all the A-pillar is roughly twice or thrice as stiff as the one from the 1-Series Coupe, while behind the two rear headrests is a "Jumpin' Jack Flash" kind of surprise just waiting for the right time to pop out. Two magnesium roll-bars painted in the same color as the interior and not looking like a roll-bar at all will automatically pop out in a fraction of a second whenever the car's gyroscopic sensor will acknowledge an imminent rollover.