BMW's 1 Series Coupe has been widely acclaimed as a latter day incarnation of the 2002 Series cars, whose success brought the company back from the brink in the early 1970s.

In that respect, the Hartge 135i Club Sport is more akin to the 2002 Turbo in circuit trim. Sitting wider and lower on Hartge's fully adjustable suspension-in this case wound right down-its wheel arches are full of 9x20-inch Hartge Classic 2 alloys with 245/30 Michelin Cup rubber wrapped around them.

Those 20s squeeze every bit of daylight from the car's wheel arches, but for everyday use as well as for the track, 19s would be a better choice. For normal road use, the coilovers would be set at the other end of their bounce and rebound scales, with a 25mm rather than 35mm drop from stock ride height. Uniball joints throughout the suspension are also outside the scope of pure road-going customer cars, but Hartge was about to pack this car off to a track to benchmark it against the more powerful factory-stock M3. The aim was to see if their lighter and more nimble car could beat its bigger brother in a straight lap-time shoot-out.

Tipping the scales at 3,400 pounds, the 135i CS has a weight advantage over its V8-rival, and a beefier torque curve on its side. Hartge's ECU remap and free-flow exhaust boost the 135i to a solid 350 horses at 5660 rpm and 354 lb-ft of torque at 2950 rpm. The upgrade gives it the same 4.8-second zero-to-62 time as the M3, and with the speed limiter function edited out, the car doesn't run out of puff until it hits 174 mph. But the real key to the 135i CS's M3-beating potential is its lower weight, greater torque at lower engine revs and trick chassis.

Most hardcore track guys would likely spend the money for the fancy but rather nice silver carbon interior trim on the console and steering wheel on more tricky bits to make the car go faster. But after the timing runs are done, this car will be returned to pure street car demo form, so the "optik tuning" parts are justified.

Hartge styling additions include a deeper chin spoiler section attached to the factory bumper, deeper side skirts, a new rear lower valance and trunk lid and rooftop-trailing edge spoilers. The kit is wind-tunnel tested and reduces lift over both axles at speed. The new rear valance extension features boundary layer fences to clean up detaching airflow, and makes space for Hartge's signature polished quad-tip exhaust system.

Climbing aboard, the first things you notice are the snug race seats with their five-point race harnesses and the lack of a back seat. The next thing that grabs your attention is the fact that the front seats are bolted in place on their rails. Although the designated driver is taller than me, I didn't have a problem comfortably reaching the steering wheel or pedals-although there's no way I'd venture on a race track like this.

The shorter Hartge gear lever gives the impression that the car has a short-shifter fitted, but there is none. The grippier, thick-rimmed steering wheel is very satisfying, the alloy pedals afford good grip, and the Club Sport takes off from rest with the tractability and finesse of the stock car.

Until you hit a bump, that is. Suddenly you're made aware that what you're driving is not a normal street-legal tuner car, but rather a track machine designed to inform its driver of every minute undulation in the tarmac. The wheel may not squirm or tramline in your palms like an old 911's, but the seat of your pants begins working overtime translating what's going on under the fat Michelins.

What is abundantly clear is the fantastic pulling power of the uprated motor. Where it falls slightly is a too-flat torque curve that makes the engine feel rather flat. Hartge's software, while keeping power levels conservative, has made response noticeably livelier, and in fact a remap that just made the engine feel like this with stock power and torque levels would be a treat in itself.

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