Not long ago, the idea of a small four-cylinder engine -- and a diesel at that -- in an expensive luxury car would have been a non-starter.
It simply wasn't done. Luxury cars were expected to have powerful V12, V8 or, at a minimum, V6 engines, not an economy oriented four banger.
Yet here is Germany's Mercedes-Benz with exactly that: a 195 horsepower four-cylinder diesel with just 2.1 liters of displacement plunked squarely under the hood of its linchpin E-Class, a midsize sedan with all the latest safety and luxury equipment that has a starting price in the $55,000 range -- way more once you stack on the options.
Mercedes is a pioneer in diesel technology. Its oil burning passenger cars date back to 1936, and as recently as 1982 eight out of ten of its cars sold in the United States were powered by diesels, mostly with five or six cylinders.
But they have never been much more than a blip on the U.S. sales charts. Many buyers in this country still think of diesels as slow, noisy, smelly, dirty and hard to start in cold weather, which was true in the past.
Some people still remember the Mercedes 65-horsepower 240D four-cylinder of the 1970s, of which it was said that you could walk faster than it got away from a stoplight. It was popular in Europe as a taxi.
But now the technology has advanced to the point where diesels are clean and quiet, start and run easily in all weather and, in many applications, are nearly indistinguishable from gasoline engines.
The distinctions that still exist are positive: because they use high compression instead of spark plugs to ignite the fuel-air mixture in the cylinders, diesels are strong and last a long time -- one reason they power most of the long distance semitrailer trucks.
They also deliver, on average, 25 percent to 30 percent better fuel economy than gasoline engines of about the same size. That's the reason the oil burners are popular in Europe, where they account for more than half of passenger car sales -- no surprise where gasoline sometimes costs as much as $8 a gallon.
Acceptance has been slow in this country, partly because diesel fuel costs more than regular gasoline. Yet as consumers become educated about modern diesels, that should change.
The Mercedes with the 2.1-liter is in the vanguard. The company introduced the engine earlier this year in its GLK compact crossover utility vehicle. Now it is available in the E250 mid-size sedan, where it delivers 27/42 mpg on the EPA's city/highway fuel consumption ratings.
That's remarkable given the tested all-wheel drive car's 4,409 pounds, or nearly 400 more than the V6 gasoline E350 sedan, which has an mpg rating of 21/30.
Yet it's doubtful anyone would choose the E250 based on fuel economy alone. The E-Class is the backbone of Mercedes-Benz, which counts on it to deliver one-quarter of its sales. Customers can choose from 13 models of sedans, coupes, convertibles and station wagons powered by gasoline, diesel and gasoline/electric hybrid engines of various performance levels.
On the road, the tested turbo diesel E250 performed admirably. Like most diesels, which deliver stronger torque (low rpm twisting force) than gasoline engines, it accelerates rapidly from a stop but is leisurely in passing on two-lane roads. There's little sound or fury; it's as composed and quiet as a gasser.
With its $54,825 price, the E250 is not a car for the masses. Moreover, it can be optioned up to the point where it carries almost all of the luxury and safety equipment found on the company's new full size flagship, the S-Class.
Standard equipment includes comprehensive safety gear, including stability control and brake assist; a seven-speed automatic transmission with a manual shift mode, automatic dual-zone climate control and a motorized sunroof.
Optional, at just $2,800, is the remarkable new Mercedes "intelligent drive," a suite of safety systems that, among other things, can detect a pedestrian and stop the car automatically. It also includes adaptive cruise control that maintains a distance from the car ahead, as well as steering assist to keep the car in its proper lane.
The test car also had packages that included active parking assistance, navigation, satellite radio, heated front seats and a rear view camera. Surprisingly, the bottom line sticker price of $64,554 did not include leather upholstery. The seats were covered in MB Tex vinyl, high quality but still artificial and sticky in hot weather.
Model: 2014 Mercedes-Benz E250 BlueTEC 4MATIC four-door sedan.
Engine: 2.1-liter four-cylinder diesel, 195 horsepower.
Transmission: Seven-speed automatic with manual shift mode.
Overall length: 16 feet.
EPA passenger/cargo volume: 109/16 cubic feet.
Weight: 4,409 pounds.
EPA city/highway fuel consumption: 27/42 mpg.
Base price, including destination charge: $54,825.
Price as tested: $64,245.