Some cars come with side effects.

At least for those of us with a touch of automotive fever.

Forget about fantasy Ferraris and lottery-win-Lamborghinis that ninety-nine percent of us will never even get to sit in, let alone own.

I'm thinking of the more attainable cars, cars that have just enough of that indefinable "something" to make you wonder what it would be like to drive one.

Like, for example, the MINI.

And let's take that curiosity one step further.

What would it be like to drive the ultimate MINI?

Well, it would be a lot like this - the 2009 MINI John Cooper Works convertible.

MINI already had a nice range of choices in their stable, starting with the base MINI Cooper in hatchback, convertible and Clubman wagon, moving up to more powerful Cooper S versions of those same three models.

The John Cooper Works (JCW) package adds another step to the model progression, taking the already impressive go-kart-like qualities of any MINI - the low centre of gravity, quick steering response and road-hugging handling - and boosting its abilities with race-inspired engineering derived from Europe's MINI Challenge Series.

MINI already had JCW versions of its hatchback and Clubman cars but it was inevitable that a soft top JCW would follow hard on the heels of the lineup's new latest generation convertible.

The John Cooper Works package starts with a 1,598-cc four-cylinder engine based on a lightweight aluminum block and bearing case and featuring four valves per cylinder, dual overhead cams and racing tweaks like sodium-filled exhaust valves. But all you really have to know is that the JCW engine supplies more power through better breathing - improved intake and exhaust flow boosted by a modified turbo with maximum charge pressure increased from 0.9 to 1.3 bar. And all that airflow is mated to a superbly efficient common-rail direct injection fuel delivery system.

The result? A 208 hp rating, up significantly from the 172 hp of the Cooper S. Maximum torque of 192 lb/ft stretches from 1,850 to 5,600 rpm. Under hard acceleration, the torque can peak even higher to 207 lb/ft via an overboost function that can bump the boost anywhere between 2,000 and 5,300 rpm. And all this contributes to a top speed of 236 km/h and a 0-100 kmh time of 6.6 seconds.

Ah, but those are just numbers.

Floor the gas pedal. The engine and twin scroll turbocharger respond with a roar. There's a brief wrestling match with the steering wheel and spinning front wheels and I am off, acceleration building, senses filling with the sound and fury of this pocket rocket taking off in lateral flight. Curves, corners, bring 'em on, as the MINI's other qualities kick in - the quick steering and immediate response, the tightened race suspension and tires that stick to the road like snot to a screen door.

Soon, I am in the rhythm, tearing through traffic like a predator through a herd, harnessing that immediacy without hesitation, sharing the roar of engine, finding the gaps, flitting from lane to lane and passing other cars like they are standing still. And it's amazing how far a small car can inflate your driving ego.

"Ha, ha! Look on my mighty driving and despair, mere mortals."

Then, of course, at the next set of lights, I almost stall as I errantly try to take off in third gear instead of first, overcompensate and shift into reverse instead of first, and almost back into the car behind me.

This is God's way of reminding me of the virtues of humility. And that the ultimate capabilities of this ultimate MINI are best explored on the race track or autocross circuit where they belong.

But even on a daily commute, if you can control yourself better than I did, you can enjoy the JCW's inherent qualities, touching on the performance aspects of a slew of dynamic improvements and technologies.

The car comes only with a race-modified six-speed manual gearbox. The Electrical Power Steering (EPS) is not only non-parasitically efficient; it can also bump up to a more aggressive mode when the driver punches the Sports Button on the center console. That same Sports Button also changes gas pedal control mapping to a sportier configuration.

The MINI JCW also has bigger brakes - 316 mm ventilated front disks and special 17-inch light-alloy wheels that weigh in at less than 10 kg each and wear high-speed 205/45 W 17 run-flat tires.

And if you want to get to grips with the technicalities of the car, you can explore a long list of technologies that includes ABS brakes, Electronic Brakeforce Distribution (EBD), Cornering Brake Control (CBC) and Dynamic Stability Control (DSC), including Hill Assist, Dynamic Traction Control (DTC) and a Brake Assist and Electronic Differential Lock Control (EDLC).

But enough acronyms, slide into the driver's seat and enjoy the kitschy ambiance of the MINI's comfortable and playful interior. The funky dials, toggle switches and soft leather seats with retro piping along the edges.

People are always asking me if I'm not cramped inside the MINI. I just step out, point at the seat and let them try it. You don't realize how much room there is in a MINI until you sit in it.

Granted, the rear seat is only for people you don't like and in the JCW there is a slight penalty to pay for the performance-stiff suspension. On bigger potholes and railroad crossings, the rattles sound like someone crashing into a tool shed. But that stiffness has eliminated any flexing or cowl-shake, the classic symptoms of a convertible.

And the soft top just suits the sporty nature of the car. The powered soft roof is well-insulated and opens and closes at speeds up to 30 kmh within 15 seconds.

The MINI John Cooper Works convertible starts at $44,000. But prices on 2010 models have actually decreased to $42,500.

Yes, that's still almost double base MINI starting prices, especially when you figure in the long list of options and accessories that can grease the approach to a $50K level.

So you have to love the MINI lineup to even consider moving up to this level of personality and performance in a small package. But for fans of the brand, in hatchback, Clubman or convertible, the John Cooper Works package adds ultimate punch to that package.

And how do you value that kind of performance?

I just have to think of the time I took the JCW into that country corner, had just enough grip to get through, accelerated and squirted into the straight...

But there I go daydreaming again.

The MINI John Cooper Works convertible.

I'm not sure if it's a cure for the automotive fever.

Or if it might just make the symptoms a little stronger.

MINI JOHN COOPER WORKS CONVERTIBLE 2009 AT A GLANCE

BODY STYLE: Four-seat convertible.

DRIVE METHOD: front-engine, front-wheel-drive.

ENGINE: 1.6-litre turbo-powered 16 valve four-cylinder (208 hp, 192 lb/ft)

FUEL ECONOMY: 7.8/5.7/6.8L100km (city/hwy/combined)

PRICE: $44,000, as tested: $48,350

WEBSITE: www.mini.ca