There’s a curious appeal to testing a prototype car.

One of the challenges of reviewing a production vehicle is to achieve a balance between the car’s mechanical characteristics, its looks, the build quality and finish, the driver friendliness, the space, the visibility and some finger-in-the-wind, gut-instinct assessment of overall appeal compared with its competitors… and probably a few other things that only spring to mind when you start writing it.

With a prototype, however, as I was able to remind myself on Wednesday when I drove the Focus BEV on the test track at Ford’s Dunton Technical Centre, there’s an extra level of freedom.

We’ve seen enough Focuses – it has been Britain’s best-selling car, after all – to have a good idea of the build quality and finish of the car… and the interior design… and the space… and the looks… and so on.