Like a child at Christmas, I could hardly wait to get my hands on the Mercedes E320 CDI.

Imagine: a fine German luxury automobile combined with the brute power of a 3.2L I-6 turbodiesel, all right here in the land of red and blue states.

As the key turned, I was rewarded with the sweetest of sounds: a very low rumble coming from the engine bay I only could liken to the purring of a conventional gasoline engine.

I stomped on the gas, and the grin on my face became a permanent fixture. The smashing torque peak of 369 lb.-ft. (500 Nm) arrives by just 1,800 rpm, pulling this 3,835-lb. (1,740-kg) sedan along at a clip that would put any V-8 to shame. Best of all, it sipped fuel at an Environmental Protection Agency rating of 37 mpg (6.4 L/100 k) highway and 27 mpg (8.7 L/100 km) city.

Judge Kevin Kelly loved Mercedes E320 CDI, but not Jeep Liberty diesel.

Having covered the European auto industry for the past three years at Ward’s, it is great to know Americans finally can experience the beauty of premium diesels that have devoured market share across the pond.

Then came a rude awakening from another highly anticipated diesel: the Jeep Liberty midsize SUV. Again, the excitement was building. I turned the key and could hardly hear myself think.

As the Liberty’s diesel rattled like a semi, I remembered Chrysler folks telling me they were looking for a diesel that would provide the best performance off-road, and that meant some sacrifices had to be made when it came to noise levels.

The Liberty produces a respectable 295 lb.-ft. (400 Nm) of torque at 1,800 rpm and 160 hp at 3,800 rpm, but does it have to be so loud? Worst of all, we tested it during relatively mild fall days. The din is likely to be excruciating when the temperature drops below zero.

It’s unfortunate the first diesel for a light-duty, mass-market vehicle from Detroit since the Reagan Admin. doesn’t stack up to Europe’s best. (Actually, it’s made by Italy’s VM Motori, which DC owns.) We’ll never break the negative stereotypes of diesels this way.

kekelly@primediabusiness.com