The back of an envelope, yesterday.
You can tell it's going to be one of those stories right away. The article (in the Telegraph, who should know better) starts with the tell-tale 'UK boffins...'. Sigh. This time round, said boffins come from Royal Holloway College, London...and they've developed a mathematical equation that tells us how small a parking space can be to allow ingress of any given car. The formula, scrawled above, contains such terms as the radius of your car's turning circle (r), wheel base (l), distance from centre of front wheels to tip of car (k) and the width of the adjacent parked car (w). Misogynists will be disgruntled to note that gender has been factored out of the formula.
Now, any time you see a news story about a ridiculous equation, it's a sure bet that there's a company's PR team lurking somewhere behind it. Indeed, we'd develop our own equation to calculate the probability of this being the case, if only some betting company would pay us to do it. Sure enough, the parking equation coincides with a motoring survey from a well-known car manufacturer that shares its name with an area of south London. The survey, whose size and distribution are not given in the press, reveals that 15% of people find parking the biggest challenge of the festive period, while 37% would rather drive on to a more expensive parking space than attempt a tricky manoeuvre. This really is awesome research. Give that team a Fields Medal.