Review: AR Plus 4 – The Sauciest Morgan

Cosworth might have designed and built the most successful grand-prix engine in history, but it also knows how to charge. Pop down to any one of the official Cosworth dealers and ask for one of its tuned-up Ford Duratec YD crate engines and you'll be lucky to see change from £10,000. Which makes the £55,000 price of the similarly engined Morgan AR Plus 4 seem rather a bargain when you consider that the standard Plus 4 model starts at £38,335. And with its red line set at 8,000rpm, has any Morgan ever screamed as hard as this one?

Conceived last year, the AR+4 is surely one of the sauciest Morgans ever to roll out of company's Pickersleigh Road works in Malvern, which lies in the evening shadow of the eponymous hills that, from some angles, look like a reclining voluptuous woman. Rortier even than TOK258, Chris Lawrence's 1962 Le Mans 24-hour class-winning Plus 4, or the amazing ethanol-fuelled, Jap-engined Aero three wheelers for which the company was originally famed.

Cosworth YD engines come in a range of power outputs from 210 to 280bhp. The Morgan application in two-litre, 225bhp form has, as one Morgan engineer put it: "pretty much everything inside thrown away and replaced."

So that's new forged pistons and connecting rods, with Cosworth's own ring pack and special bearings. The double overhead camshafts use Cosworth's Level-2 race profiles, with the company's own cylinder head assembly. Water and oil pumps are uprated, there's dry-sump lubrication and at the top end, a roller-barrel throttle assembly and carbon-fibre air box and trumpets.

The engine feeds its considerable grunt into a standard Mazda MX-5 five-speed transmission driving a solid rear axle located on coil springs, trailing arms and a Panhard rod. This set up comes from the Roadster racing models, replacing the leaf springs of the standard Plus 4 – we understand a similar arrangement might soon make an appearance on the standard Plus 4s. The brakes are uprated with cooling ducts in the front, there's a special air scoop in the bonnet and Spax adjustable dampers all round. It rides on 16-inch wheels with sticky Yokohama Advan tires and has a special 3.9:1 rear axle. While it looks pretty much like a standard Plus 4, those ghastly LED lamps are an abomination, though thankfully Jon Wells, Morgan's chief designer who thinks as we do, has demanded they are a no-cost delete option.

Aside from dodgy lamps, this has not been the simplest of conversions and some of the engineering has been tough.

"After 107 years of history you can still get caught out," says Steve Morris, Morgan's MD. "Some aspects of the build were more difficult than we thought they'd be."

Routing the exhaust was one and meant a delayed production start even though Morris had already signed a cheque for the engines. He's rather glad that all 50 are now sold.

The Plus 4 model was originally a hepped-up version of the 4/4, which was the first four-wheeled Morgan and this year celebrates a record 80 years in continuous production. The Plus 4 hasn't been as popular and was introduced in 1950 and produced in various periods since then. Most of them have wider aluminium bodies underpinned with ash timber frames and mounted on steel ladder chassis. Apart from drivetrains, major changes have been few, although the steel is galvanised these days and the wood is Cuprinol treated against woodworm and rot. With a dry weight of less than one tonne, it's one of the lightest sports cars in production.

There's not a lot of room inside the two-seat cabin, although the rear parcel shelf will accommodate a couple of soft bags or a small yappy dog. With the hood up, the view out of the windows is slightly worse than that out of a submarine and the three wipers barely swish the rainfall away. The all-black facia panel has been reconfigured from the more traditional Morgan layout, with the fuel and water temperature gauges with AR Motorsport legends in front of the driver. This redesign isn't entirely successful, with a speedometer that appears to have come from another car entirely, a clock with no numerals and that rev counter with the all-important red line hidden behind the steering-wheel rim.

There's a heater and heated windscreen and you can opt for a modern stereo radio, although you'll be lucky to hear it. While the box-weave carpet and drilled sheet aluminium trim is very much to your taste, in my short acquaintance it rather grew on me. Leather seats, which are the only practical upholstery in a Morgan, are only partially comfortable and hold you close to the Alcantara steering wheel. You'll search in vain for air bags or anti-lock brakes.

Morgan's traditional hood has confounded better brains than mine, but it has been adapted over the years with improved water and wind sealing. It'll still trap your fingers and rip your nails off if you rush putting it up and the side screens with their tommy-bar slotted knurled fixings and Perspex sliding windows are a source of bemusement for all but the most hardened Morgan driver.

Starting is a series of moves on some pointless flick switches and the Cosworth mill chunters into life, electronically-managed into grudging acceptance of modern traffic and speed limits. There's a bit of transmission shunt and you have to be careful with slightly abrupt clutch, but the Mazda gearbox is as good as it ever was and slots uncomplainingly whether you are parking or screaming up to 8,000rpm. And it's that high-revving nature which gives the AR+4 such different characters. Keep the revs low and it's a booming, slightly grumpy but perfectly manageable sports two-seater, get it above 5,500rpm and the world seems to stand still.

In fact it's slightly horrifying just how quick this car will go considering its medieval chassis includes Morgan's famous sliding-pillar front suspension. This has the advantage of giving very low unsprung weight, but the disadvantage of giving an exact correlation between body roll and camber change. In other words the roll stiffness has to be excruciatingly hard or the tyres will pick up their edges when cornering. And in turn that means that while the steering is fast and accurate and the Yoko Advans grippy and progressive, none of that matters when you are in the air, which is where you spend a fair bit of time on a bumpy road. The rear axle holds on better and relinquishes grip more progressively than its leaf-sprung sister, but it still keeps you busy. And while correcting slides is fun and relatively easy, after 20 minutes of hard driving on anything less than a billiard table, you're exhausted.

With no official performance figures, we'd estimate 0-60mph in less than six seconds and a hood-erected top speed of maybe 130mph with about 17mpg fuel consumption, a lot less if you use it hard. A standard Plus 4 musters equivalents of 7.5seconds, 118mph and 33mpg.

And the noise is as pure a struck bell, no Symposer-induced sound track here, the Cosworth mill gives it to you straight. Bit like the rest of the car really, which is bluntly honest in what it can and can't do. It's too expensive of course and it would be eaten alive by a hot hatch on an A or B road, but the AR+4 is an awesome piece of machinery and I'm still thinking about what great fun it all was. Shame they're all sold, but probably a good thing for my bank account.