Road test: 1979 Mercedes-Benz 300D.

The W123 300D has long had a reputation for longevity and operating economy. This particular example, a 1979 300D, displays 194,000 miles on the odometer. It is common to find these cars with an unfaithful or completely dead odometer but this one seems to be fairly accurate. The body shows some rust behind the front wheels, a common place for rust to start; replacement fenders are available (though by no means cheap). Another common place for rust is behind the rear wheels and in the jack points. Plugs for the jack points are available and will go a long way in preventing road salt and other debris from entering the points.

The 'thump!' of the door closing gives you an idea of just how solid this car is. The seats in this car are upholstered with MBTex and are quite comfortable but not as smooth as standard leather would be. The trade-off to that is that after nearly 200,000 miles, these seats don't have a single tear in them. European-market cars that have meandered to this side of the Atlantic often have cloth or velour interiors which are sought after if in good condition. The interior in this 1979 has held up very well over the last twenty eight years: the original Becker stereo works, the cruise control works, all the windows and the sunroof work, all the interior lights work, the carpet and the floormats aren't faded, the wood trim isn't faded or cracked but it needs to be reglued in some places, most notably the glovebox door. The dash does have some cracks (a common w123 issue) but they're not bad and the aftermarket dashpad covers them nicely, albeit not very discretely. The backseat is roomy and comfortable to ride in. The gas gauge works at its discretion.

Turn the key to 'on' and wait for the orange glowplug light to come off. A moment of silence for Rudolf Diesel, as it's been called. The car can be started as soon as the light comes off. The 1979 still uses the old loop-style glowplugs which take longer to fully warm than the later pencil-style glowplugs. Retrofitting pencil plugs to earlier w123s is easily doable.

Once the car has started there is a little knob below the instrument cluster that lets you adjust the idle, an appreciated feature that is absent on later w123s. You adjust it higher for colder weather and gradually lower it as the car warms up.

This five-cylinder oil burner transmits power to the rear wheels via a four-speed automatic, the only transmission availble in US-market w123 300Ds. European markets got four and five speed manuals - if you are looking at a manual 300D it is either a conversion (an OM617 engine in a 240D or 240D manual transmission in a 300D) or a gray-market car. As with other Mercedes' of this vintage the gear shifts are rather crisp. The transmission is sensitive to input and you have to learn to feather the pedal through shifts to get it to shift smoothly. The transmissions in these cars can start to wear out after about 200,000 miles and can slip or flare. The relatively easy task of changing the transmission oil and oil filter will significantly prolong the transmission's life.

Unless you're coming from a Fiat 850, your first impression of it is that it's not terribly fast. In fact, it's not fast at all. Which brings me to another point: being a 1979, it's normally aspirated, it's not turbocharged like later 300Ds. With the 5-cylinder engine screaming away, the best 0-60 time you can hope to achieve is around 17 seconds. That's on par with a Super Beetle.

When you do get it up to speed it's very stable. It rides smooth like any Mercedes should and the steering, commanded through an almost comically large wheel, is precise. It has adequate power to pass but it's not the freeway cruiser that the 300E was, which is to be expected.

Mercedes doesn't build cars the same way they used to in this era, anybody who owns a w123 will tell you that. They are solid, reliable, relatively easy to mend and safe even without the latest safety gizmos. With the growing enthusiast base these cars have gathered they are quickly entering classic car territory, making the w123 300D the best of both worlds if you can put up with the lackluster acceleration.

If you are in the market for a w123 odds are you will find either a 300D or a 240D (both in US-market trim), odds are its odometer will read a number not too far off from the distance from the Earth to the moon and odds are it will have several little issues that need attention; these are your run of the mill w123s. Pay extra if you find a gray-market car (especially one with coveted five-speed stick) or if you find a w123 with low mileage (e.g. sub-150,000) on an odometer that is known to be original and working. Consider service records a huge plus.

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