Heed the advice on the cover of the Hitchhiker's Guide to the Galaxy and don't panic, at least not yet. Or, maybe just panic a little on the inside, but maintain your calm demeanor on the outside.

We all make stupid mistakes. As a driver, one of the worst mistakes you can make is topping your car up with the wrong fuel. This is a task we normally complete on autopilot — we've all done it a ...