EVER SINCE THE arrival of the 2003 Mercedes-McLaren SLR and the gullwing SLS that succeeded it in 2010, extrovert styling and a lot of noise have been trademarks common to all full-blooded AMG creations. Although the current AMG GT coupé embraces this approach, it’s eclipsed in both those key areas by its new soft-top sister models.

The GT Roadster comes in two forms. Both are 57mm wider at the rear, like the hot R version of the coupe, allowing a wider track and wider wheels. They have extensive reinforcements to their aluminium bodies to compensate for the loss of the roof. Both also get the R’s active aero management, which balances the competing requirements of cooling and drag reduction.

The C also gets some R-style mechanical upgrades, in the form of rear-wheel steering, an electronic diff lock, close-ratio gearing, Race mode, performance exhaust and adaptive damping. Its power output peaks at 81bhp more than the non-C version (see right), and 35bhp more than the warm S coupe, but 27bhp less than the wild R. All use versions of the same twin-turbo V8. In town, there is no disguising the uncompromising nature of the suspension. But when the open road beckons, I twist the drive mode knob to Sport, with immediate effect: the shocks stiffen, the body crouches slightly lower, and the volume rockets up. The suspension copes remarkably well with higher-speed undulations, longer amplitudes and porous surfaces.

Mid-range thrust is simply phenomenal, with chassis accuracy and sure-footedness to back it up. Countersteer is active up to 60mph. Go faster, and all four wheels will turn in the same direction, improving stability. The optional carbon-ceramic brakes bite with vigour. The cabin uses top-notch materials, and the seats are excellent, although the cabin is a squeeze for the taller driver, and not as intuitively laid out as many Merc interiors. The roof is triple-layer fabric, available in three colours.

With the top up, the GT C is noisy enough to stir the emotions, comfortable enough to eat the miles. When you lower the roof via that fiddly toggle switch above the rear-view mirror, it gets mighty windy at speed. At £139,445 it’s a lot of dough, but for now the soft-top is a better deal than the less potent coupé, and in terms of value for money, it even eclipses the R-spec coupe.