They can’t help it. They can’t leave it. Most manufacturers, if making a roadster variant of a coupé like the Exige, would whip off the plastic roof panel, replace it with a removable canvas one and leave things at that.
Lotus did the roof thing (saving 10kg in the process), and also removed a front splitter and rear spoiler to make the Exige roadster looking cleaner in the process. Job done, then? No, no, no. Not at Lotus.
You see, the body changes affected the Exige’s drag coefficient (by a tiny 0.04 Cd) and reduced the Exige’s downforce. And that really bugged Lotus’s engineers.
So, over the fixed-head Exige (which is magnificent, incidentally), the Exige roadster gets a stiffer rear anti-roll bar and more rear negative camber, with less negative camber at the front, to compensate for the aerodynamic changes and leave the rear tyres feeling just as planted, at speed, as those on the Exige S coupé.
And it’s this unbending attention to dynamic detail that makes a Lotus drive like no other. And the Exige S roadster is, as a result, every inch as magnificent as the coupé.
In some ways, it is more so. The first open-top Exige we tested was left without the Race Pack that had been fitted to every coupé we’d driven. It was a touch softer, and the geometry changes meant that it steered with more ease, and that made it an utterly fabulous road car.
It flows, with the compliance and suppleness that is the hallmark of the best cars from Hethel. The steering is still a bit heavy at parking speeds, but that’s a small price to pay for the levels of communication it offers on the move. This is a terrific car. Oh, and the roof comes off.
Log on to Autocar.co.uk again tomorrow where we'll continue our rundown of the best cars of 2013.