The outgoing 5 series, launched in 1989, itself was no slouch, a benchmark luxury-performance sedan continually improved such that seven years into its lifespan it still was judged an industry standard. The '97 is larger (wheelbase, at 111.4 ins. [283 cm] is 2.7 ins. longer), stronger and more equipment-laden -- yet lighter overall.
Innovative material usage is one of the big stories here. The one-piece bodyside stampings contribute to a design that boasts a 29-Hz figure in that much-lauded new body engineering totem, the natural frequency response. It's 82% better than the old car in torsional rigidity, 40% improved in the bending mode. Remember that the old 5 series already was one stiff mother of a design.
BMW says use of high-strength steel is now 40% weight, compared with the old car's 12%. The stiff-body stuff usually comes with a horrendous weight penalty (reference Ford Motor Co.'s new Taurus and General Motors Corp.'s Oldsmobile Aurora), but the new 5's bodyshell weighs just 20 lbs. (9 kg) more. So despite all the increased stiffness, the new 528i is 56 lbs. (25.5 kg) lighter than the old 525i, the V-8-toting 540i weighs the same.
Preponderantly responsible for the new car's overall weight savings is the '97 5-series suspension, which just happens to be constructed completely of aluminum -- a first for a volume passenger car. BMW says the aluminum suspension is some 70 lbs. (32 kg) lighter in total than the steel suspension it replaces -- despite the fact that the car also incorporates a new, more complex 4-link rear suspension in place of the previous car's simpler trailing-arm arrangement. The so-called "integrated rear axle" is borrowed from the rear suspension designs used in the 7- and 8-series models.
Engines, too, are enhanced. Gone is the 2.5L inline six and the charming little 3L DOHCV-8 the old car enjoyed, the engine selection now being whittled down to just the 2.8L inline 6-cyl. (really the old 2.5L) and the 4.4L DOHC V-8, also enlarged from last year's displacement of 4L. The 2.8L (190 hp) is reworked to deliver slightly more power and improved torque in more useful speed ranges; the 4.4L V-8 (282 hp) puts out the same power as the old 4L, but lays down a healthier torque spread.
Six-cylinder models are fitted with either a 5-speed manual or a 4-speed electronically controlled automatic transmission. The 540i transmits the power through a 6-speed manual or a 5-speed auto-shifter.
Standard tech equipment includes ABS, traction control and BMW's stability enhancing braking system that selectively brakes single wheels to "influence" cornering dynamics. The effect is almost magical.
Along with an almost embarrassing wealth of standard interior comfort/convenience items, the new cars offer side-impact air bags -- standard for the V-8 equipped cars and included in an optional premium equipment package in the 6-cyl. models. BMW will supplement the doormounted air bags next year with an "inflatable tubular structure" air bag arrangement that gives additional side-impact protection for the upper-torso/head area.
Despite the luxury-sport sedan's rather extravagant new technology and host of standard features, BMW says that on an equipment-adjusted basis, a typical 1997 528i costs 6.9% less than its 1996 counterpart. Base price for the 528i, powered by the improved, 2.8L version of the long-standing 2.5L inline 6-cyl. engine and equipped with a 5-speed manual transmission, is $37,900. The new model's price range is topped by the 540i, at $52,000, about the same price as the 1996 model.
Thirty-eight grand seems hugely competitive. It's tough to imagine anyone needing more than even the base 528i delivers. The reduced unsprung mass and rigid bodyshell combine for an uncompromising ride, augmented by the expected high level of only-BMW-can-do-it handling. The stability-enhancement system's a gem; it and the new rear axle design entertain no nonsense from any high-speed maneuver. The only downside is the 540I's wispy recirculating-ball steering rack. Even MercedesBenz AG, long the foremost proponent of "the ball," has switched to rack-and-pinion steering for its new E-Class sedans.