Mercedes-Benz hit its stride with the mid-range E-Class in 1985, introducing a number of features which are taken for granted today. The 1986 300E featured a fuel-injected SOHC 3-liter six-cylinder engine developing 177 bhp. Although it was a big, heavy luxury car, it could outperform contemporary sports cars like the Porsche 944 and IROC Camaro, with a top speed of 140 mph and 0-60 mph in 7.8 seconds.

The E-Class was faster than the larger S-Class 380 and 500 models, but could also be driven carefully to manage 30 mpg on the highway. Most came with a four-speed automatic, while a five-speed manual gearbox was a rare option early on. ABS was standardized in 1985. The 4-Matic all-wheel drive system was offered from 1990-93 in the U.S., and was considered state-of-the-art.

The W124 replaced the blunt W123 and featured a coefficient of drag as low as .028 thanks to the aerodynamic nose, smooth body and belly pans. The five-link rear suspension is now commonly used and a semi-Citroen rear system was self-leveling. It used struts and gas spheres, though the ride height was fixed, and maintained by coil springs at rest.

The single wiper employed an eccentric cam to enable to to sweep almost to the windshield corner. Optional rear headrests could fold down when not needed to improve visibility. The exhaust was also fitted with the first oxygen sensor to enable the engine to run more efficiently.

Progress was steady and subtle. A passenger airbag arrived in 1989, the interior was upgraded in 1990 and the stereo improved in 1991, the same year that ASR traction control was introduced. ASR used the brakes to slow slipping wheels and was so sophisticated that it practically replaced the heavy, expensive and complicated 4-Matic system in all but the most severe conditions.

A 300TD turbo diesel wagon was offered in 1987, while the 177 bhp gasoline powered version replaced it in 1988. Both have four-speed automatic transmissions. Both have self-leveling rear suspension and can carry 1,250 lbs.

For those looking for performance, the short-wheelbase 300CE coupe arrived in 1988, with plastic lower body cladding. It gained variable valve timing a a four-valve head in 1990, while the transmission was revised in 1991 to start in first gear instead of second, for a considerable improvement in performance. A 217 bhp, DOHC 3-liter engine was fitted in 1993 and the coupe was renamed the E320 in 1994.

The E-Class raised the bar significantly for mid-range sedans, coupes and wagons and good examples remain handsome and competitive today. That said, there are some problem areas. The air conditioning is notorious for automatic climate control problems, the switch pad can fail, and compressors are fragile. The Becker Grand Prix radio is also unreliable. Early cars need valve seals to be upgraded to Viton, while alkaline U.S. antifreeze can attack the plastic pipes.

Deferred maintenance can be frustrating and expensive, as almost all systems are complicated, including accessory belt drives, suspension flex discs and ABS brakes. Expect thorough records and insist on a pre-purchase inspection.