Distinguishing an original performance trim from an upbadged showroom model requires checking functional components. Cosmetic trim pieces are easily swapped in a home garage, but powertrain and cooling upgrades require serious investment.
| Model & Generation | Factory Powertrain & Output | Exclusive Factory Hardware | Base Model Contrast |
|---|---|---|---|
| BMW 325is (E30)1987, 1991 | 2.5L M20B25 SOHC I6168 hp / 164 lb-ft | 25% mechanical LSD (3.73 ratio), M-Tech I/II aero, sport suspension, bolstered seats | Base 325i featured an open differential, softer suspension valving, and flat comfort seats. |
| BMW 318is (E30)1991 | 1.8L M42B18 DOHC 16V I4134 hp / 127 lb-ft | M-Technic suspension, disc brakes on all four corners, lightweight balance (~2,600 lbs) | Standard 318i sedans possessed rear drum brakes and base commuter suspension settings. |
| BMW 335is (E92)2011, 2013 | 3.0L N54 Twin-Turbo I6320 hp / 370 lb-ft (overboost) | Secondary water cooler, 850W fan, stiffer engine mounts, M-performance exhaust, optional 7-speed DCT | 2011+ base 335i shifted to single twin-scroll N55 engine (300 hp) and standard 6-speed automatic. |
