"What on earth are you doing?" asks McLaren's chief test driver, Chris Goodwin, as he finds us rooting around the inside of a P1 with a tape measure.

We're recording cabin dimensions, pedal offsets, that sort of thing. Goodwin isn't the first industry executive, nor will he be the last, to be surprised that we subject all our cars to precisely the same array of assessments when we do a full road test.

That means a McLaren P1 gets its insides measured. And that means a 0.9-litre Renault Clio gets sent around the handling circuit. Why? Not because of the lap time, obviously, but because the circuit we use is a handling course, not a race track; we designed a testing layout that tells us how a car – any car – behaves in extremes.

Understeer resistance, high-speed lane change stability, stability under emergency braking in bends, traction, electronic safety system performance, brake durability and more can all be assessed, in safety, in minutes. That's relevant to every car on the market.

As you move to more performance-orientated cars, though, the little number that pops out at the end takes on an increasing relevance, obviously. Of cars we've hitherto road tested, the fastest around our chosen layout of MIRA's handling circuit was a Radical SR3 SL, at 1min 8.0sec dead.