Cadillac STS 4.6 V8

Despite the badge's history, there is a perception that the US manufacturer is unable to produce a genuine BMW and Mercedes rival. But that has not put it off - which is why engineers have spent the past four years on a development mission, thrashing a prototype of the STS saloon across Europe.

Cadillac now believes it has a model capable of exorcising memories of unwieldy and poorly finished cars such as the front-wheel-drive Seville - and is ready to launch its flagship on this side of the Atlantic. Expectation is high - and Auto Express took to the wheel of the STS to see if it is justified.

The car is certainly substantial. Slab-sided in profile, the saloon is six inches longer than BMW's 5-Series, plus wider and lower. But Cadillac has worked hard to ditch the Yank tank image. Chrome trim - beloved in the US - is absent and the fussy and cluttered tail looks less messy in dark, solid colours.

Inside, the leather and wood dash blends well with the console "infotainment" unit and air-con buttons. However, fit and finish is not on a par with the Audi A6 or new Lexus GS. Details such as the over-sensitive electric steering wheel adjustment irritate, and the door pockets have a naff, rubbery finish.

The big Caddy bristles with hi-tech gizmos, from adaptive radar-controlled cruise control to a head-up instrument display. On the road, the technology is not intrusive, and the STS feels more compact than its bulk implies.

Powered by a 325bhp 4.6-litre V8, the rear-wheel-drive machine has a five-speed auto gearbox, as well as uprated steering, suspension and braking, which combine to make it surprisingly nimble.

Downsides include a lack of chassis feedback in sweeping corners, plus a tendency to fidget over uneven surfaces in sports mode. The V8's likely ΂£42,500 price sounds a lot, but this car shows US engineers have listened, learned and applied important lessons.