Mercedes A45 AMG

In isolation, the A45 is an impressive achievement. Few machines this side of a supercar deliver as much performance, while the four-wheel-drive chassis provides staggering all-weather grip. Aggressive looks and a racy cabin complete the A-Class’s hot hatch makeover. Yet it’s hard to look past the car’s wallet-bashing £37,845 price.

Mercedes doesn’t have the rich hot hatch heritage of its traditional rivals, but that hasn’t stopped it pulling out all the stops for the A45 AMG.

On paper, the racy newcomer has all the raw ingredients to become the fastest pocket rocket ever. For instance, under the bonnet is a 2.0-litre four-cylinder turbo engine that pumps out a thumping 355bhp, while the addition of an electronically controlled four-wheel-drive system means the A-Class should be as fast through corners as it is in a straight line. The A45 looks the part, too.

The rakish and eye-catching lines of the standard A-Class have been given a muscular makeover courtesy of a subtle bodykit that includes deeper front and rear bumpers, a tailgate spoiler and a unique AMG grille. Further clues to the car’s range-topping status include a pair of rectangular exhaust pipes, 18-inch alloys and large, cross-drilled discs for the upgraded braking system.

Our car also featured the £2,550 Carbon Trim Package, which adds the lightweight material to the front splitter, side sills and rear diffuser. Incredibly, this expensive option doesn’t include a carbon fibre finish for the door mirrors – you’ll have to fork out another £1,230 for this styling tweak.

Inside, the A45 has been treated to an equally racy upgrade. Neat additions include eye-catching red trim for the distinctive eye ball air vents, a flat-bottomed three-spoke steering wheel and figure-hugging, high-backed Recaro front seats.

Yet while the cabin is more sporty than the BMW’s, it can’t match its rival for premium appeal, as some of the plastics feel a little low-rent. Still, there’s little to separate our two contenders when it comes to kit. You get all the essential equipment, including climate control, Bluetooth and a DAB radio, while illuminated AMG door sills and an ambient lighting package give the interior a classy feel at night.

However, as with any Mercedes, it’s easy to get carried away with the expensive options list – our lavishly appointed test car weighed in at a bank-breaking £51,245. As with the standard A-Class, the cabin is reasonably roomy, with back seat passengers getting a similar amount of head and legroom as in the BMW – although both trail spacious rivals such as the VW Golf and Audi A3.

Yet the Merc’s combination of thick C-pillars, shallow side windows and bulky front seats mean the rear bench has a claustrophobic feel. On the plus side, a wide range of seat and steering wheel adjustment means it’s easy to find the perfect driving position.

Twist the key in the ignition, and the Merc’s 2.0-litre four-cylinder burbles purposefully into life. The turbocharged engine’s gravelly soundtrack is no match for the snarling BMW, but what it lacks in character it makes up for in explosive performance.

Four-wheel drive and a launch control system allowed the A45 to go from 0-60mph in 4.3 seconds, which was a full seven-tenths faster than the M135i. Yet while the AMG and BMW share the same muscular 450Nm torque output, the Merc’s is delivered nearly 1,000rpm higher, at 2,250rpm.

As a result, it feels a little sluggish at low revs and it wasn’t as responsive during our in-gear tests. For instance, the seven-speed A45 took a yawning 16.9 seconds to accelerate from 50-70mph in top gear; the eight-speed BMW needed just seven seconds flat. Keep the revs above 2,000rpm, though, and the A45 is brutally fast.

You can overtake slower traffic in the blink of an eye, while the twin-clutch gearbox provides rapid-fire upshifts accompanied by a distinctive parp from the exhausts. Unfortunately, the transmission isn’t as effective on downshifts, as it sometimes fails to respond to the metal paddles mounted on the steering wheel.

Cheekily, Mercedes charges £570 extra for the alloy shifters, which replace the standard plastic items. Still, in automatic mode, it’s smoother than the occasionally jerky BMW. And while the AMG’s steering isn’t as sharp as the M135i’s, it’s accurate and more naturally weighted.

The Merc also boasts more grip, allowing you to carry huge speed through a series of corners, while the four-wheel drive tames wheelspin even in slippery conditions. Completing the impressive dynamic display are powerful and progressive brakes and rock- solid body control – although the trade-off for this high-speed composure is a very firm ride. Yet despite the towering performance and composed handling, it’s not as much fun as the BMW. Factor in its hefty £37,485 price tag, and the A45 has its work cut out in this contest.