This probably sums it up on the 3 series line of evolution in regards to US models:
E21= great entry into the sport compact luxury line, a smaller version of the 3.0 csl. Underpowered with the I4 but still a great chassis. Lots of quirks and rattles. Typical of a new model entry. Used both I4 & I6 engines.
E30= huge leap in technology and refinement going into the 80-90s, took advantage of better EFI, abs, LSD, disc brakes, chassis tuning. IMHO, the crown jewel & best 3 series from BMW in terms of authentic driving experience with no artificial driving assists. Used both I4 & I6 engines.
E36= another leap in technology, design and refinement, took advantage of OBD I & II, I6 engine only, VANOS. Carried over most of the technology advancements from the E30. The last mostly mechanical/hydraulic 3 series BMW built.
E46= great refinement above the previous model but not a leap. Fixed the quirks and rawness of the E36 such as the rattles and loose parts that would occur over time. Took advantage of Double VANOS, more advanced and refined suspension nannies- asc/dsc, abs; however it eliminated the LSD on everything except the M3. Fly-by-wire technology added which detracted the linear response of the older mechanical/hydraulic system; added a delay in response and precision but was minimal compared to the E9x with variable steering. IMHO, this was the best and most refined compromise for an authentic classic driving experience with minimal electronic nannies assistance. Used I6 engines only.
E9x= target market -> mainstream, totally different path towards the evolution of the 3 series. Took advantage of FI engines- turbocharging, variable steering, adaptive suspension, stiffer chassis even if the body got longer, bigger and heavier. The FI engines are great masterpieces, best part of the E9x evolution. They responded similar to an 8 cylinder engine with the fuel economy of a 6. The stiffer chassis made great improvements in limit driving & safety; however, the driving experience became too harsh with not enough refinement or feedback (whole car dynamics was skewed). It felt like they couldn't find the perfect balance with the engine, chassis & suspension that the E46 perfectly refined from the E36. Suspension tuning was geared for the more aggressive, probably to also compensate for the FI engines. Steering input added variable steering which added to the non-linear feel of the fly-by-wire along with more loss of precision; probably over compensation by the new tech. The interior was revamped to the more common driver oriented full controls vs the all passenger concept of keeping all the controls accessible from the center of the car. Since it was their first foray it was expectedly low quality for a first effort. Cabin insulation also seemed to be increased so external decibel levels weren't as high; numbing the sensory experience. However sometimes you need to hear the tire squeals and engine revs as a confirmation of what your hands and feet are feeling.
F9x= target market -> even more mainstream Lexus crowd. New technology are turbocharged I4, adjustable situational settings, regenerative braking, auto start/stop, dynamic handling (variable steering assist & adaptive suspension). The F30 is the closest thing to a Swiss Army knife BMW, it allows you to customize your ride depending on your driving style an mood. Unfortunately, due to this please all target it compromised on the BMW driving experience of old- the sportiest setting isn't close to the ultra aggressive E9x or the perfectly refined E46 or raw E30. It sort of falls in between the E90 and E46; imho, this is due to the extra size and weight gain of the car. The current F30 is as big and heavy as the old E39 5 series from the early 2000s. The dynamic handling package is great for people who don't make the driving experience a priority and rely on the electronic nannies to make them a better driver. The interior has improved with the F30, way better than the E90. All in all the F30 is a good all around car which just needs improvement on the top end sporty experience.
Last edited by av98; 11-03-2012 at 12:42 PM.