After the revealing iPhone 3GS tests, all the internet has gone mad with different phone resistance tests. But these guys have taken these tests to another new level. They have used four iPhone 4S and four iPhone 5S as brake pads on a Porsche 911. 
Long story short, they fitted the devices to a 2002 911 that had a big brake kit and started their test. At the 20 mph, the iPhone did a great job, but then everything turn out to be a big mistake.
Watch their incredible test here.