In fairness, the air intake and gas caps look dangerously similar on a Smart ForTwo.
A scary incident recently happened in the UK when a woman became trapped in a 2005 Smart ForTwo that erupted into a fireball while filling up at a gas station. Luckily, mother of two Julie Nicklin escaped unharmed thanks to builder Brian Turner who dragged her out of the car just in time before the gas tank exploded, in what sounds like a cliched action movie scenario in real life. A video posted by the The Sun shows the aftermath of the explosion which caused people nearby to run for cover.
In this case, a vehicle fault wasn't the cause of the fire – the driver mistakenly poured gasoline into the engine's air intake port instead of the fuel tank. Consequently, the fuel was ignited when she turned the ignition causing an immediate explosion, filling the interior with flames and trapping her inside. Brian needs to be recognized for what he did," Nicklin said. Everyone else had run away and I couldn't get out of the car - he saved my life. I couldn't get out because I had parked so close to the pump. The car is completely destroyed and all my clothes were burned - apart from my jacket which was an expensive one."
In incidents like this, it's easy to blame the owner for being inept. However, as Jalopnik points out it's a surprisingly easy mistake to make because the Smart ForTwo has a design flaw where the caps for the fuel filler and air intake look remarkably similar, as shown in a comparison image Jalopnik put together. It's a well-known issue that owners have been complaining about for years. You could argue, though, that the driver would surely have noticed the difference between removing the round center cover from the air intake to flipping open the fuel filler door. You would also think they would have memorized which side of the car the fuel filler is located.
While there is text on the side of the air intake cap that says "No fuel," it's barely visible. Smart clearly needs to make them more distinguishable to prevent a fatal catastrophe like this incident so easily could have been.