BMW's stringent durability testing was the main factor in the Works package's numerous delays (originally it was due to be launched at the Paris show in September last year) but it has also assured that the Works kit is both beautifully engineered and doesn't affect the fantastic MINI TLC servicing deal. It needs to be very good, though, because it costs a whopping ΂£3010 plus fitting. Call it ΂£3500. Expensive with a capital F.

However, you don't simply get a chip and tweaked supercharger. The Cooper S Works gets a completely new cylinder head with improved porting to help dispel gases and heat as quickly as possible, freer-flowing stainless steel back-boxes, and an all-new supercharger as well as the necessary ECU upgrade. Of course, there are also the obligatory 'John Cooper Works' badges and an aluminium engine cover to further differentiate the ultimate factory-approved MINI.

Mike Cooper (son of the late John Cooper and now chairman of the company) is confident that the Works kit will prove the only reliable performance upgrade for the MINI. In hot weather testing simply making the supercharger work harder - as many rival tuners do - saw calamitous engine failures due to excess heat build-up. This shouldn't be a problem in the UK, but it's comforting to know that all eventualities have been considered during the kit's
development.

The end result of this thoroughness is 197bhp at 6950rpm and 177lb ft at 4000rpm. BMW says these figures translate into a 0-62mph time of 6.7sec and a top speed of 140mph. Very impressive - but how does it compare with the Hartge power upgrade (΂£1761) as fitted to our very own Cooper S?

Well, in terms of absolute performance there's very little in it. An unscientific drag race from 40mph in third right into the meat of fourth saw the Cooper S Works pull about a car's length lead over our Hartge-equipped S. However, our car was at a slight disadvantage, being loaded up with camera gear. Crucially, though, the Works car feels and sounds keener at any speed.

Cleaner throttle response and instant pick-up from low revs also set the Works car apart. The Schnitzer MINI we tried recently had a similarly muscular delivery but faded where the Hartge car really started to work hard - the Works kit, on the other hand, never feels breathless and the mid-range torque is matched by a real ferocity when you're clinging on to every last rev. It doesn't sound quite as strained as the other tuned MINIs, either. The supercharger whine is exaggerated but over 5000rpm it's accompanied by an urgent, hard-edged exhaust note. The cutesy MINI suddenly sounds likes it's cutting at the air - and dispatching it angrily when it's used up all the energy it has to give.

On the evidence of this first drive we'd say the Cooper S Works is a success. The engineering integrity of the kit is unquestionable and it endows the S with not only a huge slug of power but also a slightly sinister character. It may look a bit girly but a little provocation unleashes a darker, hard-charging side that will never fail to entertain. Hartge, Schnitzer and other tuners can offer similar power for significantly less, but BMW isn't worried - it knows demand for a factory-approved 200bhp Cooper S will be massive.

Worldwide, 3000 Works kits will be sold by the end of 2003 and 3500 a year thereafter. Other Works accessories including 18in wheels (΂£1645 complete with tyres) and sports seats (΂£764 each for full leather) are also available. Something approaching ΂£3500 is a huge amount of money for an extra 36bhp, but customers are queuing up for the Works treatment. Money doesn't seem to be an issue; just before the press launch Mike Cooper sold a new Cooper S Works with every conceivable extra for ΂£35,000. The world really is going MINI mad.