Mirad lo que he encontrado en un foro: http://www.bimmerfest.com/forums/showthread.php?t=145276 The Z4 M Roadster made a big impression on us at its international press launch in Spain last month. Fast, fierce and more thoroughly engineered than the Z3 M, its hotrod ancestor, BMW's latest M3-engined two-seater instantly asserted itself as a very serious contender in the £40,000 sports car sector. Consequently, as soon as we returned to the UK we began pestering BMW GB for more time in the car. Our tenacity paid off when we were given the opportunity to borrow an M Roadster direct from BMW's Munich office. Naturally, we jumped at the chance. But what to test it against? There's one very predictable rival to the M Roadster that simply can't be ignored: the Porsche Boxster S. So long the sports car benchmark, Stuttgart's recently rejuvenated mid-engined roadster is immaculately executed and oozes prestige and refinement. But with a modest 276bhp, it's vulnerable to the M Roadster's raw thrills and rippling muscle. If the diligent, mild-mannered Porsche is the Clark Kent of the group, then the TVR Tuscan Convertible is its alter ego. Carrying on where the late, lamented Griffith 500 left off, the drop-top Tuscan is a welcome return to what TVR does best: producing heart-pounding, window-rattling, back-to-basics, old-school sports cars, packed with snorting straight-six power and remaining refreshingly initial-free with a complete lack of ABS, DSC, PASM, EBD or any other electronic BS. If only the price was as old-fashioned. Fooled by the highly tempting basic Tuscan Convertible's list price of £39,950, we thought the TVR might hold a keen price advantage once options on the other cars were taken into account, but we hadn't bargained on quite how basic a £40K Tuscan is, or the extent to which this test car's lavish specification would jack-up the price. The biggest shocker is the £8500 Sport Pack, which comprises an uprated 380bhp engine (15bhp and 20lb ft up on standard), firmer suspension, bigger brakes, close-ratio gearbox, air-conditioning, 18in 'Spider' alloys, big-bore sports exhaust and gas-discharge main-beam headlights. Add to that £3000-worth of chavtastic 'Cascade' paint, £1000-worth of full-leather interior, 17.5 per cent VAT on all the options and £750 delivery, and the total price is an astonishing £55,387.50. Compare that to the desirably specced M Roadster and Boxster, both costing around £46,000 as tested, and it's clear the TVR has its work cut out before it even turns a wheel. And to think we ruled out the £50K Mercedes SLK55 AMG for being too expensive... We've got one more contender up our sleeves, though, one that tees up a fascinating in-fight between the official M Division product and that of factory-endorsed fettler Alpina. Since its introduction in 2004, Alpina's Roadster S has carved itself an enviable niche as the quickest and best-sorted 'approved' Z4 available. Powered by an enlarged 3.4-litre version of BMW's previous-generation M3 straight-six, the hand-built motor trades ultimate power for a hearty slab of mid-range torque, but still packs a handy 295bhp punch. This particular car, kindly loaned to us by evo reader Steve Davies, is a Lux model, which adds satnav, more leather, xenon headlights, cruise, and a set of distinctive 19in Alpina Dynamic alloy wheels to the Roadster S inventory. He also specified Alpina's £600 'Sport Pack', which means thicker anti-roll bars front and rear and a 1 degree increase in front negative camber. Costing £40,450 as tested, the exclusive and classy Alpina is the unexpected bargain of the group. There's a bittersweet twist to the Roadster S tale, though, for Alpina has had to cease production due to BMW stopping the supply of the engine block on which its 3.4-litre unit is based. BMW blames emission regulations, but it seems a striking coincidence that production should end just as the M Roadster is launched. The good news is that UK Alpina specialist Sytner still has a handful of new Roadster Ss in stock at £37,850. Hurry while stocks last, and all that. So we've agreed on the contenders, but where to drive them? Finding great driving roads in Germany is notoriously difficult, finding great roads with a broad mix of surfaces and a decent variety of corners is almost impossible. Coupled to a tight schedule and blighted by wintry weather forecasts across northern Europe, we consult the map and search for an approximate midway point between Calais and Munich, eventually settling on the small town of Nürburg, nestled in the Eifel region of Germany. You may have heard of it. Day one is spent almost exclusively on the motorways of England, France, Belgium, Holland and, finally, Germany, before we peel off the autobahnen and onto the fast, smooth and sinuous secondary roads leading to our hotel in Adenau. Relaxed in the knowledge that day two will bring plenty of opportunity for fast driving on some of Germany's best roads, we stick to our respective steeds for the duration of the journey - Steve Davies in his Alpina, John Hayman in the Boxster S, yours truly in the Tuscan, and Henry Catchpole, who'll be joining us later, on an easyJet flight to Munich. The next morning dawns mercifully dry and bright, if bitterly cold. As we head out onto the wooded, undulating Eifel roads, I'm pleased to be in the Z4 M. Partly because it's got heated seats and it's -2 degrees outside, but mainly because it takes all of two minutes to appreciate that it combines all the fizz and fury you'd expect of a 338bhp Z4 with genuine everyday usability. It's an intimate, compact cockpit, and the black-leather scheme of our test car should make it dour and claustrophobic, but thanks to the bold architecture and excellent driving position, sitting in the Z4 M is like being in a snug cocoon. Ergonomic gripes begin and end with the overly fat steering wheel, which Henry likens to a giant leather donut. Leaving Adenau behind us, we're immediately in the thick of some serious uphill hairpins. The surface is smooth, which helps the M Roadster work to best effect, summoning impressive traction, even in sub-zero temperatures. The DSC system is relatively easy to trigger, but unless you're particularly brutal it's quick to release its electronic grip, and if anything it's the nose that's likely to relinquish its grip rather than the rear. Of course, switch the DSC off and, given the right corner and the correct provocation, the Z4 M will slide, but you need to be determined to overcome its neutral to nose-led stance, not to mention decisive to smoothly balance the resulting slide with the throttle and counter-steering once the M diff hooks-up. It's the helm that's partly to blame for this, for although the Z4's standard electronic power-steering set-up has been ditched in favour of a hydraulic system, it's still not as good as is should be. Steering responses are more consistent, but detailed feel is still lacking and the weighting is excessive, forcing you to manhandle the M Roadster through tight corners. That said, as miles and experience build, you're filled with the sense that here is a Z4 that actually reacts cohesively, rather than the disjointed front-followed-shortly-by-the-rear feeling you get from the Z4 3.0i. Junking run-flat tyres for a set of ContiSportContacts on 18in rims certainly helps the M Roadster stay in sync with the road surface, and you can feel each corner working hard to generate more and more grip before finally and progressively fading as you approach and then breach the limit. Composure deteriorates on bumpy roads, the suspension getting increasingly busy as pace increases, but in truth the M Roadster is rarely badly wrong-footed. Ultimately, while it can't wholly absorb the punishment from a pockmarked road, prudence will trim your speed before the chassis runs out of talent. As you'd expect, it's the crackling 338bhp, 3.2-litre straight-six that dominates proceedings. Louder and more effervescent than I recall, throttle response is instantaneous with plenty of gutsy urge on-tap, and the top-end rush is more vivid and apocalyptic than ever. There's no doubting it's more than capable of head-banging into the 155mph limiter, while the claimed 0-62mph time of 5.0sec seems a little pessimistic. The gearbox, with its snappy, short-throw shift, is a great partner for the sparkling six, and the brakes, while laughably grumbly (in finest M tradition) and a little over-servoed at the top-end of the pedal travel, stand up well to fast road driving. All in all, the M Roadster has laid down an impressive marker. It makes sense to jump straight from the M to the Alpina, for the differences, and similarities, should be particularly striking. As in the M Roadster, the first thing you notice about the Roadster S is its engine. Deeper sounding, with a softer, less acute throttle response, the hand-built 3.4-litre engine is more evenly muscular and effortlessly potent, with a great surge of sweet power from 3000rpm that keeps it in touch with the M and a few metres ahead of the Boxster. The steering (electric rather than hydraulic here) is lighter and more delicate, making it easier to make small adjustments to your line, but it too lacks satisfying, granular feel. It's not as consistent either, with less feel at low speed than high, but at least you can get your hand around the steering wheel's rim. The brakes are carried over from the 3-litre Z4. They don't grumble and groan like the M Division items, but nor do they offer the outright stopping power either, and in truth are no more than adequate on a 165mph car. The lack of a limited-slip differential also softens the Alpina's dynamic edge, and frustrates in the hairpins by delivering oversteer through one bend, scrabbly inside-wheelspin the next. In fact, it's the biggest source of inconsistency in the whole car. The ride is sharper edged, thanks in part to those 19in rims, but there's plenty of smooth-road grip and composure, and less initial body-roll. Charging over the same lumpen surfaces that agitated the M Roadster's chassis results in a more extreme reaction from the Alpina as it struggles to maintain control of vertical wheel movement, getting crashy where the M merely bobbles. As Alpinas are usually noted for being supple and well tied-down, this is disappointing. Perhaps BMW stuck with more modest 18in alloys on the M Roadster for a reason. We've been criss-crossing the roads that surround the Nürburgring all morning, some tight and twisty and broken from repeated freeze-thaw action, others smooth and flowing. What's surprised me is that despite their differences, all four cars appear evenly matched. The M Roadster's ferocious pace is tempered by its need for revs, the Alpina's accessible torque and weight advantage keeping its cousin honest. We'll come to the Tuscan later, but for now I'm entranced by how the Boxster relies on its balance and brakes more than brawn, scything through the corners with wonderful precision, lithe damping and measured steering responses enabling you to carry more speed from turn-in to exit. It's a cerebral rather than visceral process, one that encourages you to take clinical lines and blend your inputs until you can barely sense the moment you begin to steer into a corner or straighten the wheel, or where you release the brakes and depress the throttle. Of course, with 'just' 276bhp and 236lb ft of torque, there's not much of a fight going on at the back wheels, especially with the optional 19in wheels and PASM suspension (each option adding around a grand to the price of our test car). Consequently you can get back on the power earlier and harder than in the other three cars without fear of unsettling the chassis. Although, to be fair, the Boxster chassis could clearly cope with 300bhp or more without breaking sweat. You can feel that the Boxster is wearing wide rubber, for it nods and bobbles over bumps, but it maintains excellent body and wheel control, and feels deliciously taut and fluid. It's got terrific part-throttle and high-speed balance, giving you the confidence to keep your foot in, even when you're waiting for the corner to open out. The downside is that, thanks to the lack of poke, there's not much difference between half and full throttle, and you certainly don't get the impression that you're having to meter out the power. When chasing the M Roadster, Alpina or TVR, you spend quite a lot of your time with your foot pinned, which is telling. Enjoying the Boxster to the full relies on an empty road, for only then can you wind it up and keep it there. Driving it illustrates the difference between the kind of slow-in fast-out style you adopt in the abundantly powerful M Roadster, and truly carrying speed. Both styles have their moments: the purist finding lasting pleasure in those rare moments when the Porsche is flowing free, the pragmatist revelling in the M Roadster with a simple flex of the right foot. The same is true of the TVR. Of all the cars here, the Tuscan is the one that best captures the spirit of a sports car. To a man, whenever we climb into it our driving styles become more exaggerated: gratuitously blipping the throttle, howling off down the road and deliberately inducing the cacophony of pops and bangs on the overrun. As Steve accurately says: 'The TVR is a car for extroverts, or those who would like to be.' Unsurprisingly, the Tuscan is a totally different experience to both Z4s and the Boxster. It's alive in your hands and underneath you, a machine that relies on human inputs rather than those of a computer. It grunts and snuffles and coughs at low speed, bellows and roars at high revs. The gearshift is lighter than TVRs of old, but retains that delicious sense of oiled metal teeth meshing together, while the brakes have an almost unservoed level of pedal feel. With some 380bhp, 310lb ft of torque and just a claimed 1100kg to propel, the Tuscan should feel ballistic, but as TVR fresher Henry rightly points out, 'You wonder where all the power is - until you discover you've only been using about an eighth of the seemingly endless throttle travel.' On second thoughts, perhaps that's a good thing, especially when anything like full throttle breaks traction effortlessly on the cold German tarmac, sometimes even in third gear. Compared with the Tuscan coupes we've driven in the past, the Convertible's chassis is a big improvement, thanks largely to a bit of engineering Vallium having been applied to the hypersensitive steering. Now at least you can sneeze without fear of spinning, but still, by any normal standards, the Tuscan's front end is absolutely nailed to the road. Understeer never enters the equation, and while this is fun through the tight second-gear stuff, long, quick corners can be sweaty-palmed affairs as you attempt to nudge the nose in towards the apex without tipping the tail into a nasty twitch of turn-in oversteer. With no electronic driver aids to save you, this is high-performance driving from a bygone era, your every sinew focused on just how much power the rear tyres can cope with under power, your ears, hands and feet straining to sense the onset of lock-up under braking. On a smooth road it's thrilling and extremely rewarding, but on our now-familiar stretch of wet and bumpy tarmac, the challenge (and fear) is draining, for the TVR remains dynamically unsorted much beyond seven tenths. Force the pace and it bangs and crashes, bucks and slews, its thin veneer of composure peeled back to reveal a ragged, jagged, ill-tempered chassis. Such on-limit dynamic flaws are too big to ignore, or forgive. And yet, if you're easily seduced, you can almost kid yourself that it doesn't matter, for the TVR delivers in so many other ways. The noise, the intimacy, the animalistic engine, the lunging, the noise, the sense of connection, the sheer physicality of the thing. Did I mention the noise? Seriously, unlike the others, the Tuscan works its magic from the moment you fire it into life. Yes it can be infuriating, like when the seatbelt decides to strangle you, or when you notice that the analogue speedo's increments are obscured by the binnacle at 80mph and only reappear at 140mph, but it's also got a brilliantly simple hood arrangement, a huge boot and a great big heart pounding away on its sleeve. As you can probably tell, it's a hellishly tough call to separate these four contrasting, entertaining and genuinely exciting sports cars. Had the TVR not been hobbled by a ludicrous price-tag, it might have been harder to separate it from the top two, and easier to downplay its failings. Let's not forget that, up to a point, it's a much-improved car, but you simply can't ignore a £55K price tag, especially when you're talking about a car that's lacking the detailing and integrity that's expected at this price point. Cheaper, sweeter, classier and more rounded in its abilities, the Alpina's harder to criticise and easier to recommend. Ultimately, though, it fails to assert itself over either the Boxster S or the M Roadster, its chassis lacking the fine-tuned compliance and precision to out-handle the former, its engine unable to deliver the searing, edgy performance of the latter. That leaves us with the two major players. Objectively, the Boxster S should win. It copes more convincingly with a wider range of roads and conditions thanks to polished damping, silken steering and a benign, infinitely adjustable on-limit balance. It's not challenging but, given a clear road, it is totally absorbing. However, if you've stepped out of the M Roadster, TVR or even the understated Alpina, the Porsche feels a bit flat, lacking poke and playfulness in this company. The M Roadster will win friends as much for not being a Porsche as for its visceral appeal, vivid character and much-improved dynamics. It could look more distinctive, and it doesn't set a new benchmark for sports car dynamics (that accolade still belongs to the Boxster), but it's a bold, ballsy car that exhilarates and challenges in a way the oh-so-accomplished Porsche can't match. In a magazine that lives for the thrill of driving, that's enough to give it the nod by the narrowest of margins.