Like many modern cars, the Audi has a central rear armrest that folds down into position. However, no opening through to the boot is then created - a steel panel remains in place behind the leather trim. A hole for the subwoofer grille could have been cut in the plate using a jigsaw equipped with a metal-cutting blade, however...

One of the major problems with car subwoofers is that they take up a lot of space. A small, well-designed subwoofer enclosure fills about forty or fifty litres but the situation is in fact even worse than that.

When you locate a large, square box in the boot, you find that lots of the nooks and crannies that were previously available to be filled by soft bags are now impossible to access.

...when the interior boot trim was pulled away, a factory pre-cut opening was revealed. In some markets this car is equipped with a "ski port", but in this particular model the plate was not fully cut out. Some judicious use of an angle grinder soon removed the short pieces of metal that held the blanking panel in place, allowing the easy creation of a rectangular opening.

The other major drama with a conventional car subwoofer is that it’s heavy. By the time you incorporate thick MDF panels and the driver itself, you can easily have added 40-50kg – weight whose fare you pay for at the petrol pump every time you fill up.

So how have we overcome these problems?