Behind the flashy car reveals at the Frankfurt motor show there's an underlying layer of angst from the car makers at the amount of work needed to meet the paperwork requirements for the new WLTP emissions regulations.

The scheme is ramping up over the course of the next year, but one of the requirements is that each spec change must be separately tested, in order to give buyers a more accurate indications of what's possible with the various configurations of engine, gearbox, air-con and so on.

Explained: Autocar's guide to the new WLTP and RDE economy and emissions tests

On paper that seems fair enough, but think about the complexity of some of today's car ranges and you'll start to understand the potential headaches and the increased legwork and paperwork, not to mention the added cost.

Imagine, too, being one of the many manufacturers to have followed Mini’s lead and added numerous personalisation packs and options into the mix. Not all will require re-testing  - the go-faster stripes don’t all need assessing - but the bigger ticket options certainly do. And that means a mountain of extra complexity.

The result, so the whispers suggest, have so far been two-fold: firstly, a rush to get as many new cars through testing prior to the 1 September test date as possible, earning the manufacturers an additional 18 months to undergo the new WLTP regime. There’s also an increased likelihood of some cars being quietly withdrawn from sale further down the line, possibly to return once testing is complete.