Air Kraft: DTM preview

Pick one of three DTM cars you see here at random - the chrome Merc C-Class coupe, for example - and you'll find it has 25 wings. Twenty- five. Roll that figure around in your mind for a minute, and compare it to other bewinged inventions - a 747, for instance. That's only - technically - got five. British Touring cars, the UK equivalent of Germany's DTM, have just one. If there were a world championship for wings, the DTM would sew up the podium every time.

But every single flick and flap has a purpose. This year more than ever, because the DTM - Deutsche Tourenwagen-Meisterschaft, to give it its full title - will be contested for the first time by the cars you see here. The German Big Three. Mercedes vs Audi vs BMW. The three biggest rivals in car manufacturing will all be hammering the same bit of tarmac with full works backing. Three makers that strive every day to launch a road car that bests the others.

And now they're going racing.

Words: Piers Ward
Photos: Ripley & Ripley

This article was first published in the February 2012 issue of Top Gear magazine

Merc will be competing with the C-Class Coupe, Audi will bring the A5 and BMW will return to the DTM with the M3, in a season with a new set of rules designed to create more exciting and more affordable racing. It should be the perfect recipe for touring cars, in a series where there could be as many as six British drivers competing in a championship most people in the UK have never heard of.

The 2012 regs have changed to keep costs some 40 per cent lower. So DTM organisers standardised over 50 parts - stuff like the carbon chassis, the Hewland paddle-shift gearbox, the dampers and the steering rack - which means that all three manufacturers will effectively just pick these bits up off the shelf. It also means new-boy BMW shouldn't be too far behind championship stalwarts Audi and Merc, because it won't have to spend as long developing the complicated bits. Mind you, the engine is still unique, and that won't be an easy job.

Ah, yes. There is something about looking at these DTM cars and being able to identify them as racy versions of things you see tooling down the high street; these cars have about as much to do with regular commuter tools as Veyrons do with London buses. Just because it looks like a steroidal version of the C-Class Coupe or A5 parked on your drive, don't for a second think that's the case. Study a DTM car really hard, and you'll notice just two similarities - the door handle and the rail where a roof rack would go. Other than those two tiny details, every other bit is different. Jump in a BTCC car, and you'll recognise stuff, like the air vents. You don't even get a ‘dash' in a DTM car - it's a carbon pod.

And if you think you're cheering on a maker for engineering the best car: don't be fooled. You're cheering for much more subtle stuff than that. Set-up is king. Which means that fine-tuning all that very obvious aero has never been more important - the pernickety detail is where races will be won and lost.

Aerodynamics is the darkest of the dark arts of engineering. Seemingly innocuous surfaces can have the most dramatic effect. Engineer and driver must be in constant synergy: one speck of a degree of change to any of the multifarious wings, and the balance of the car will be completely altered. Even those tiny dive planes on the front valance make a huge difference - if there's a need for a low downforce set-up, they're removed altogether. Everywhere you look there's a lip or edge. The cars are literally sprouting stuff all over the place and it's likely those surfaces haven't stopped breeding, either: those 25 wings are likely to multiply before the season kicks off on 29 April at Hockenheim. It's all about trying to direct the air, make it hit each body surface in a particular way to get the most out of the bulging, almost-recognisable shape.

As a result, a 2012 DTM car should produce about 1,000kg of downforce at the rear wing. That's like having a Ford Ka perched over the back axle. And that figure doesn't even include the effect of the diffuser. That's the big tray that stretches for 2m under the car - half the length of the vehicle - channelling air under the belly of the beast to aid stability. Because the diffuser is so long, it should make the cars very balanced around their centres.

Yet despite all those wings, there is actually less aero-induced grip than last year. Less aerodynamics means a greater reliance on ‘mechanical' grip - instead of relying on the wings to stick the car to the track, the drivers will be depending on the tyres. And that means the holy grail of motorsport - more overtaking. If the car in front isn't ‘stealing' as much of your downforce - and therefore grip - then you can get closer in faster corners. The 2011 cars were on the edge, especially in qualifying, but because the Hankook tyres are larger than the Dunlops used last year, the cars should be more stable.

Gary Paffett, Merc's leading driver, the most successful current racer in DTM and a Brit unknown by 99 per cent of the country, reckons it will be more fun. "Slower corners will be harder work, because we'll be going quicker. But because we've now got a six-speed paddle gearbox, we'll be able to upshift in the corners and push much harder." Pushing harder, in racing-driver speak, means having more fun.

But more fun for the driver doesn't necessarily mean more fun for the fan. The key test will be whether the changes actually do create more overtaking opportunities. Slipstreaming is notoriously difficult in DTM because it's tricky to get a tow off the car in front - hopefully, the increased emphasis on mechanical grip will make it better. Because while the racing is close, Paffett recognises that the changes are needed. "It's a great challenge for the driver and the team, but it's too much of a procession. The fan needs more excitement."

Is there anything he'd change? "I wish we had more power. That would make it more interesting because of the extra mechanical grip." Sorry, Gary - you want more power? The 4.0-litre V8, revving to 8,500rpm and producing about 500bhp in a car weighing 1,050kg, isn't enough for you? No, you're right: 0-62mph in about 3.0seconds and a top speed approaching 200mph is a tad sluggish.

That shows the calibre of the DTM driver. This series continues to attract the next-big-thing in racing - Paffett nearly got the nod for the McLaren Formula One seat, but Hamilton pipped him to it, Paul di Resta was DTM champ in 2010, Hakkinen has raced in it, Coulthard will be competing next year, as will, er... Ralf Schumacher. Well, you can't have it all.

The reason it attracts such a high standard of racer is that it's relatively easy to switch from DTM to single-seater because they handle similarly. Paffett himself is a full-time test driver for McLaren. The DTM's full carbon chassis runs wishbone suspension all round with in-board pushrod dampers, which is more akin to a single-seater set-up than a BTCC car.

There's other deliciously trick stuff as well. All the cars are fitted with a brake cooling system, so when the driver comes into the pits for a tyre change, they can press a button on the steering wheel that dumps water onto the brake disc, as they are no longer being cooled by air alone.

Quite how the drivers know where their pit box is is another matter - even the seating position bears no resemblance to the road-going version. You sit so low and so far back that the view out of the windscreen is mostly sky, and getting in involves a level of gymnastic ability that Beth Tweddle would be proud of. Paffett has concerns about his lack of vision: "It's worse this year because you're more enclosed. We haven't done any mirror work yet, but it's definitely trickier to see out of." Sorry - mirror work? Yep, even the mirrors on a DTM need setting up.

But that's the thing: a modern DTM car is designed for one thing only. To race. There's brain-frying attention to detail, precision and engineering purity, in a car that looks like it was designed by a loon. It's the paradoxes that make it so brilliant. The cars are recognisable, but exciting. Almost attainable, but eyes-wide extreme.

So roll on, Hockenheim. And imagine the fever at the first corner. So much investment, so much rivalry - all that shared history between Audi, BMW and Mercedes, and all of it boiled down to a strip of tarmac 10 metres wide. "Win on Sunday, sell on Monday" never had so much pressure attached.