Geo tried to market the Storm as somewhat comparable to the Mazda RX-7 and Lotus Elan. It wasn't by any stretch but drivers often treated it that way.
The now mercifully dead brand of Geo was introduced by GM in 1989 as a range of horrible compact captive imports which GM just couldn't bear to see wearing badges of any of its existing brands. It's true that none of these cars were exactly the sort of thing you'd want to rely on in a crash, but the Storm is the one which earned its place on this list by virtue of seeming something like a performance car, but being in no way able to back up that claim. The Geo Storm is actually a rebadged version of the Isuzu Piazza, or Impulse as it was known in the US.
A Holden-badged version was also sold in Australia, but the Geo version is unquestionably the worst. This is because GM was trying to push the Geo as having an economy/environmental image, and a genuine performance car would have conflicted with this image. So although there was a turbocharged and all-wheel-drive version of the Isuzu with a Lotus suspension that was actually kind of fun, the Geo received only bottom-of-the-barrel parts. The Geo version of the car, introduced in 1990, was actually the second generation of the Piazza, and used a different platform than the original car had.
This new platform was something of a step down from the predecessor, and when it debuted, Holden decided to drop the model from its lineup. Although the car was built by Isuzu, there was quite a lot of GM influence in the design, and much of the chassis design was influenced by the work GM had done with Lotus the previous year on the then-new Elan. This seems like it would be somewhat promising, but the watered-down Geo was an absolute cow. Performance was less than exciting, with a base engine that produced 95 horsepower and an optional more powerful DOHC version that made 130.
There were a couple years where an optional 1.8-liter 140-horsepower engine was offered in place of the DOHC 1.6-liter plant, but this didn't last long. The car was actually pretty light, weighing just 2,200lbs, and the 1.8-liter could reach 60mph in 7.1 seconds, not a completely terrible time for such a cheap car in the early Nineties. Geo used to brag that the handling capabilities of the Storm were roughly in line with those of the RX-7 convertible. Now a comparison with the RX-7 is understandable, but Geo doesn't seem to have realized that comparing its hardtop coupe's handling to that of a convertible isn't a great way to brag.
This is where a lot of the problems came from, the car was targeted at young people who didn't necessarily understand that this wasn't a performance machine. The styling was very much in keeping with the performance cars of the day, and they might have even heard words like Lotus and RX-7 being thrown around and attached undue levels of importance to them. The Storm therefore became the standard bearer for the overconfident driver, a demographic which is seemingly always about to have a huge accident. Studies have shown that when an automaker builds both a sedan and a wagon version of the same car, the wagon version always has a much lower accident rate.
This isn't because of any mechanical advantage in the wagon, but simply that wagons attract more cautious drivers. In much the same way, the Storm didn't offer crash results that were particularly worse than the rest of the Geo lineup, but it was by far the most likely to be involved in an accident. The NHTSA actually rated the Storm as having the most aggressive drivers in its class. That's not to say that it did well in crash tests though, because it didn't. Passengers in particular were at a very high level of risk when their idiot friend behind the wheel who thought he was in a Lotus wrapped his car around a tree.
So although the Storm was admittedly pretty mediocre in the safety department, it was its tendency to attract morons which cemented its reputation as a death trap.