Building a "World car" is trickier than you might think. With 7 billion of us now on the planet it's fair to say that a lot of different people have a lot of different requirements from a car.

Ford already knows this. Its first attempt at a "World car" was in the 1990s, with the appropriately-named Mondeo. A success in Europe, it was much less popular in the U.S. where it arrived in altered form as the Contour, where it didn't really catch on.

The Ford Focus is different. Once again designed in Europe it was initially drip-fed into the U.S. market to replace the Escort and ZX2 for a few generations, before a global launch for the current model meant 120 countries all around the world would be getting essentially the same car.

It's not easy to build a car that fits everyone though, even if you can get performance, safety and pricing right. Customers in the German and American markets are a lot taller than those in Asia, for example. And a 200-pound man will have very different comfort requirements from a 100-pound teenage girl looking for her first car.

Ford used 3D data from thousands of individuals in the European, North American, Chinese, Japanese and South American markets to create computerized models with accurate dimensions.

Ford engineers then used this data in computerized car models to ensure drivers and passengers of all shapes and sizes could sit in comfort, space and safety.

If you've ever wondered why smaller cars are getting bigger, Ford has the answer to that too.

“As well as the broad regional variations, the latest 3D body data also reflects the fact that, on average, the global population is getting taller and heavier, and the new Focus interior takes account of this trend," explains Ralf Nürnberg, Ford's attribute leader for Occupand Accommodation.

Designers of the Focus have even gone to great lengths to ensure the interior layout is suitable for different cultures - with door pockets that don't only take the 1.5-liter water bottle that a European customer may want, but a tea container that Chinese customers might require.

The maximum tailgate height can also be varied, with lower settings in countries with a lower average height.

The net result? The global Ford Focus is suitable for a 97.5 percentile of the global population. In other words, of the 7 billion people on our planet, 97.5 percent of them could get comfy in a Focus. Though not all at once, obviously...