So what exactly are the differences between a 325e and 325i? Why do some models have an “s”, like a 318is, 325es, and 325is? Is the ’84-’85 318i the same as the ’91 318i? What’s a 325iX? And why do the M3s look so different than the rest of the E30s? This guide will attempt to explain the differences between US-spec E30 3-series, which was sold in the US from 1984 to 1991 (except for convertibles – more on that below).
325e vs. 325i
The primary differences between the 325e and the 325i are in the engine and drivetrain. Although both models have engines from the same M20 family, the 325e has more displacement than the 325i (2.7 liters vs. 2.5), but drastically less horsepower (121 vs 167).
The “e” denoted “efficiency” and was referred to as eta, the Greek character, and was the first time BMW designed an engine specifically for the U.S. market. When development of the engine started during the gas crisis of the 1970s, the engineering targets were set to accommodate needs of American drivers – high torque to allow for quick off-the-line acceleration, high highway efficiency to satisfy the mindset of fuel-conscious consumers, and a refined, smooth experience that American luxury vehicle buyers expected.
A high-revving, autobahn-friendly engine (like the one found in the Euro-spec E21 323i) was deemed out of target due to the lower speeds of U.S. highways, still heavily constrained by a national 55 mph speed limit.
BMW engineers took an unusual approach to meet the targets by developing an engine that ran at lower RPMs to reduce frictional and pumping losses and maximize torque at lower speeds, resulting in the eta’s large displacement, high torque, flat torque curve, low horsepower, and low maximum engine RPM – 121 horsepower, 174 lb-ft of torque coupled to a very tall 2.93:1 final drive (2.79:1 for earlier models). The eta had the power and efficiency characteristics of a diesel engine with the smoothness of a gasoline engine.
However, by the mid 1980s, favorable fuel prices and shifting buyer tastes to more powerful engines led BMW to release the sport-oriented 2.5 liter 325i in mid-1987. In contrast to the 325e, the 325i had a hotter cam, dual valve springs, larger valves, larger intake manifold, larger throttle body, larger exhaust manifolds, dual pipe exhaust system, more advanced engine management system, and lightweight flywheel, along with a shorter 3.73:1 final drive (4.10:1 in some automatics). The resulting 167 horsepower, 164 lb-ft of torque, and high revving 6700 RPM engine became the standard for BMW 3-series engine dynamics that carried through to 2007.
325 (with no letters)
Any model that is simply badged “325” with no letters is equipped with the 2.7 liter eta motor. It was BMW’s base model from 1986 until 1988 when it was phased out in favor of the 325i. In its final year, the 1988 325 (dubbed “Super Eta” by enthusiasts) was equipped from the factory with a 325i cylinder head, unique pistons, 325i exhaust system, and Motronic 1.1 engine management control, which bumped horsepower up to 127 and raised the redline to 5500 RPM.
The 318i was the base model in the E30 lineup from 1984-1985 and again in 1991.
The 1984-1985 318i was equipped with the M10 1.8 liter SOHC inline-4, first seen on the 1969 BMW 1800 and revised for use on the E21 3-series, capable of 101 horsepower @ 5800 RPM. It used a simple L-Jetronic fuel management system, as opposed to the more modern Motronic system used on the 325e, 325i, and M3, and came with very limited standard equipment. By 1985, the M10 reached the end of its lifecycle and was hard pressed by its competition, so BMW dropped the 318i after only 2 years of service.
The 318i returned for 1991 and featured an all-new 4-cylinder engine with a similar high-revving character as the 325i. Rated at 134 horsepower and 127 lb-ft of torque, the M42 1.8 liter DOHC 16-valve 318i coupe and sedan were in production for the 1991 model year only, though the M42 318i convertible ran to 1993. The M42 (and updated M44) engine continued service in the E36 3-series until 1998, when BMW once again dropped the 4-cylinder engine from the U.S. market.
318is, 325es, 325is
Any E30 with an “s” suffix, such as 318is, 325es, and 325is, denotes the sport model which only came in 2-door form. It can be easily recognized with its front spoiler with integrated foglights, rear decklid spoiler, and (for 1987 and later) 14″ BBS cross-spoke “basketweave” style rims. “s” models also feature a limited slip differential (optional on the 318is), bolstered sport seats, thicker front and rear swaybars, slightly stiffer shocks and front springs, and a leather-wrapped 3-spoke steering wheel (except 1990 on, which had a 4-spoke leather-wrapped airbag wheel). The 325es and 325is were well-equipped with an on board computer, power windows/mirrors/sunroof, central locking, and a premium sound stereo system. In 1991 there was no official 325is model, although all of the aforementioned items were still available as the Sport package.
The “X” denotes all wheel drive and only came in 325iX form (there is no such thing as a 325eX or 318iX). It shared major components with the 325i but used a different oil pan and front struts due to its front drive axle. These changes led to a 9mm wider track than the RWD 325i and necessitated unique wheels, so all 325iX models came standard with 15″ BBS cross-spoke rims with deeper +41 offset as well as flared fenders and side skirts to accommodate the wider track.
The “c” denotes a convertible, although it is not official BMW nomenclature. Rather, it is used by dealers and owners to easily identify a convertible model.
BMW introduced the 325i convertible in 1987 and the 318i convertible in 1991; both of which remained in production through 1993, 2 years after E30 coupe and sedan production ended (as the successor E36 convertible was yet not ready for production until 1994).
Convertibles had significantly larger rocker panels to compensate for the loss in structural rigidity. As the 325iC was the most premium non-M variant in the 3-series lineup, it was fully equipped and the only E30 model with available heated front seats and the only non-M3 model with horizontal seat stitching.
318iA, 325eA, 325iA
Similarly, “a”, as in “325iA,” is used to identify an automatic-equipped car and is not official BMW nomenclature.
The racing-derived M3 was released in the US for the 1987 model year with a unique powertrain and body. It had 20 different body parts than a comparable non-M E30 and is easily identifiable with its flared fenders, body colored bumpers/moldings/mirrors, front spoiler, side skirts, rear valence, rear decklid spoiler, high trunklid, rear window clip, and roof-mounted antenna.
The S14 2.3 liter DOHC inline-4 engine was intended for motorsport use and derived from the S38 3.5 liter DOHC inline-6, later used on the M5. It featured a very peaky 7100 RPM redline, 10.5:1 compression ratio, 4.10:1 limited slip differential, and close-ratio gearbox. For track use it also had a larger fuel tank and 5×120 15″ BBS cross-spoke rims to accommodate the upgraded brakes – thicker and larger diameter ABS-equipped ventilated discs, larger calipers, and a larger master brake cylinder.
Interior upgrades were limited to red gauge needles, an oil temperature gauge in place of the fuel economy gauge, 3-spoke sport steering wheel, leather sport seats, rear armrest (replacing the center rear seat), and an M logo on the instrument cluster and shift knob.
Early vs. Late Model E30s
The E30 was sold in the US from 1984 to 1991 (1993 for convertibles) and received a styling refresh in 1988 and again in 1989. They are often grouped by the early, 1984-1987 pre-facelift style or the late, 1989-1991 post-facelift style. 1988 styling was a single-year hybrid.
1984-1987 coupes and sedans can be easily identified by their large aluminum bumpers and black rubber bumper covers. These prominent bumpers were BMW’s solution to meeting the U.S. Phase 2 requirements – that is, it had to withstand a 5-mph impact with virtually no damage.
Other visual characteristics of the 1984-1987 coupes and sedans were bumper-mounted front foglights, vertical reverse lights, a small rear valence, black body side moldings with aluminum accents, and a rectangular center high mounted stop lamp (CHMSL).
1989-1991 coupes and sedans can be easily identified by their body-colored plastic bumpers that met the rolled-back U.S. Phase 1 requirements (from 5 mph to 2.5 mph). Other late model styling updates include a deeper front valence with integrated foglights, larger rear taillights with horizontal reverse lights, a prominent rear valence, a lower rear wheel arch, all-black body side moldings, and a trapezoidal CHMSL.
1988 coupes and sedans had styling that was a mix of both early and late models. It had the early-style aluminum bumpers that were shortened to comply with the 2.5mph impact requirement, black rubber bumper surrounds, but late-style front valence with bumper-mounted foglights, larger rear taillights with horizontal taillights, a prominent rear valence, and a lower rear wheel arch.
Convertibles followed similar styling updates but at different production times. From 1987-1990, the 325iC had early-style aluminum bumpers (but with body colored bumper covers) and from 1991 to 1993 the 318iC and 325iC adopted the late-style appearance. All convertibles had the lower rear wheel arch found on the 1988-1991 coupes and sedans.
The M3 did not receive a styling update throughout its lifecycle.