In July 2013 I was in the bowels of Nissan Europe’s Barcelona technical centre doing something rather innocuous. Or so I thought.

I was doing some early reporting under a long-lead embargo on the development of the second-generation Nissan Qashqai, for an article that wouldn’t be published until the following April.

As part of a whistle-stop tour of the various facilities and departments involved in the Qashqai’s development, the engineering whizzes took us into a chamber where they set the official economy and CO2 figures for their cars.

From the group of us visiting the facility, they wanted a volunteer to have a go at part of the test. My hand shot up the fastest.

So I have played a hands-on role in one of the infamous official economy tests. Here’s what happens.