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I've reached that dangerous point in life when so many things that happen remind me of things that happened long ago. I think the medical term for it is Old Fuddy Duddy Syndrome. It sends young people fleeing in disgust and even friends start making excuses about how they just remembered they have to be somewhere else in a hurry.

The scheduling of this E320 CDI diesel prompted just such a moment. My mind was flooded with memories of southern Virginia in the early 1970s, which was where I made my first acquaintance with a Mercedes diesel. It belonged to the family that owned the local appliance store. They operated the Esso gas station, too, which adjoined, but the sons ran that. Mom and Dad managed the appliance store, and they were a unique Southern type: the Small Town Intellectual.

Towns all over the South had them and not only tolerated them, were even proud of them — so long as they knew their place. And most of them did. Being big intellectual fishes in small ponds is what had attracted them in the first place. Anyway the father of the family that ran the appliance store in my small town in Virginia had advanced degrees in some science. I don't recall what. But he was the only man who could fix the electricals on the 1963 Studebaker Avanti I then had.

The Raymond Loewy-designed Studebaker Avanti was one of the most exciting and influential cars of the decade. Great fun to drive, too. Unfortunately, though, the one I owned had been assembled in the dark. The electricals, in particular were a constant source of trouble and there were no longer any Studebaker dealers to turn to. I must have been sharing my misery on an ad call — a small town newspaper editor did a little bit of everything — for the father of the family offered to have a look. Before I knew it, I found myself in the bizarre position of taking my Avanti to an appliance store for regular service. While I was there, not surprisingly, we discussed cars — mostly Avantis and Mercedes diesels.

Back then, the reason for going diesel was economy of operation, pure and simple. There was no other incentive. Diesels were noisy, smelly and SLOW. Still, when the repeated fuel crises of the 1970s produced periodic gasoline shortages and rapidly escalating prices, the diesel engine enjoyed a brief vogue. This was helped considerably by the decision of General Motors to climb on the bandwagon in a big way. Soon, tens of thousands of GM-built diesels were clattering down the nation's highways. Just as soon, they were clattering into GM dealer repair shops needing expensive repairs or engine replacements. And tens of thousands of GM diesel owners were swearing up a storm — but mostly swearing never to buy another %$#@$ diesel. Millions of non-diesel owners got wind of their angst and swore off diesels, too. And the diesel boom died almost as soon as it had begun.

Pity, because the technology — kept alive by certain European makers, such as Mercedes — has continued to steadily improve. If you haven't driven a diesel lately, it is an eye-opening experience. The E320 CDI, for instance, behaves like a non-diesel in virtually all respects. You might say the E320 CDI speaks gasoline with merely a trace of a diesel accent. The only thing that gives the game away is a hint of diesel clatter when you start the engine — especially when it's cold — and a bit of diesel growl when you tromp the accelerator. You'd certainly never know it from the acceleration, which fully on a par with what you would expect from a gasoline engine of similar displacement. As for the diesel smell…what smell? This car very nearly meets gasoline engine standards for emissions. If diesels had been this good twenty-five years ago during the diesel boom, we'd all be driving them today.

The turbocharged six-cylinder engine features full electronic fuel injection, considered technically impossible in a diesel until only recently. The "CDI" in E320 CDI stands for Common-rail Direct Injection, a term denoting the fuel line loop supplying constant, very high fuel pressure to each of the six solenoid injector valves.

The leap to electronic fuel injection means that the E320 CDI engine can be cleaner, quieter and more powerful than conventional mechanically-injected diesel engines. This is especially important in terms of emissions, which is a major hurdle Mercedes has to face in the next couple of years. Diesels inherently produce 20 to 30 percent LOWER carbon dioxide emissions and significantly lower carbon monoxide than gasoline engines, but, historically, diesels have produced more oxides of nitrogen, plus soot and particulates. With the precise electronic control of fuel delivery of electronic fuel injection, the E320 CDI can pass current 45-state emissions standards. Mercedes engineers are optimistic that the CDI diesel will be able to meet emissions standards in all fifty states when low-sulphur diesel fuel becomes available in the US in the latter part of 2006.

Fuel prices have stabilized over the past twenty-five years — so much so, in fact, that the real cost at the pump (allowing for inflation) is actually lower than it was in 1980. But the fuel economy is still there in a diesel car or truck. The gasoline-powered E500 4Matic we recently tested was rated at 20 mpg on the highway test cycle. The E320 CDI diesel — essentially the same car — is rated at an astonishing 37 highway and, in some ways, an even more impressive 27 mpg in the city cycle. And this is for a midsize luxury machine with all the comfort and convenience a decent person could want.

The base price on our test car was $49,795, including destination charges. To this, they had added nearly eleven grand worth of options, most of them unnecessary. The power sun shades and the automatic trunk lid alone added about a thousand dollars, for example. I would have slashed the list to include the leather seats ($1,500) and the Entertainment Package ($970), which comprises the Premium Sound System and the CD changer. At $52,265, the resulting car would have been very nicely equipped and represented solid value. R&D