Cadillac XLR

To perfectly pigeonhole the XLR, think of GM’s new premium roadster as Cadillac’s SL500.

Like its Mercedes rival, the XLR’s a flip-top, two-seat V8-powered convertible that’s so well equipped there are no options… beyond choosing the colour.

Cadillac’s second attempt at dethroning the SL – remember the late ’80s Pininfarina-styled Allante? – begins with look-at-me edgy styling, largely taken from Brit designer Simon Cox’s 1999 Evoq concept.

The plastic body, with folding steel hard-top, slots over the very rigid C6 Corvette platform and gets the excellent 4.6-litre 326bhp Northstar V8, much modified for this longitudinal application, driving through a new five-speed automatic.

Double wishbone suspension and the quickest-acting adaptive dampers ever prove that Cadillac has put some serious engineering muscle into the car. According to Cadillac’s figures, the XLR’s 1653kg undercuts the SL500 by an impressive 180kg.

Here are all the ingredients to take on the SL, and Jag XK and Lexus SC430. And so it proves on the road. The Caddy is quick, effortless and surprisingly agile, with a deep American V8 burble from the exhaust as the engine sings to the 6500rpm red line. You need to listen for the gear changes, because you won’t feel them.

The ride, far firmer than you might expect from a Cadillac, is well controlled and gives the car a strong sporting character. It feels bigger than an SL – though the exterior dimensions are virtually identical – but the driver quickly adapts to the long, wide bonnet.

On centre, the steering is light. Move the huge leather and wood trimmed wheel a couple of degrees and it weights up nicely and feels responsive, the chassis well planted. Yes, the XLR’s good to drive, with plenty of grip and a stability control system that is hard to provoke. If the ride lacks the finesse of the Mercedes-Benz, the XLR always feels secure.

The car also feels strong – Cadillac says the torsional rigidity is better than that of any rival – and well made. Even so, the interior isn’t quite up to the price or the competition in terms of materials and fit and finish. The cockpit just doesn’t feel special. Many occupants find the windscreen header rail intimidating: it’s too low for tall people and too close, creating the impression that the cabin is confined.

The XLR has two serious flaws. The boot is tiny when the roof is lowered. Roof erect, the boot is bigger than any competitor, but there’ll be no driving al fresco to the golf club in this Caddy. And without any form of wind-blocker – an amazing omission given the other toys fitted as standard – turbulence in the open cockpit is nasty from as low as 70mph.

Peter Robinson