Driving Euro diesels from Audi, BMW, Chrysler, and Mini

More than half the cars sold in Europe are high-mpg diesels. So given the opportunity to sample four models directly from the Continent, we hoped to find out if modern European diesels are good enough to entice American drivers.

Small-displacement engines with big torque and fuel economy numbers have long been considered forbidden fruit to the U.S. market. With the revised, ultra-low-sulfur fuel recently adopted in the States, we are seeing a slow influx of European diesel models reach our shores. Mercedes-Benz and Volkswagen have lead this wave of new diesels, and several other automakers have announced plans to bring more here.

So, what do we have to look forward to? We got a taste last week by attending the annual International Motor Press Association (IMPA) track days at Pocono Raceway, where we piloted several imported diesel models provided by Bosch. We sampled four European-market diesel models: 2009 Audi A4 3.0 TDI Quattro, 2007 BMW 123d hatchback, 2007 Chrysler 300D, and 2008 Mini Cooper D. (Bosch supplies some of the fuel injection and emissions control equipment for these cars that allow them to meet stringent air quality standards in Europe. They say the cars could also be made 50-state compliant in the U.S.)

In our review of the Mercedes-Benz E320 Bluetec diesel last year, we raved that its modern diesel engine was not only clean, but also felt as smooth and powerful as a gasoline engine. (Watch our video road test.)

In driving the four European cars at IMPA, it is clear that modern diesels are much smoother and quieter than those engines Americans may remember from the 1980s. But not all are as refined as gas engines, or as that E320.

I was very impressed with the Audi A4 3.0 TDI. This A4 has 236 hp and a whopping 369 lb-ft of torque, giving it impressive acceleration. The car was also quiet, relaxed, and refined in driving on the street. It’s rated at a combined 36 mpg on the European fuel economy test cycle. And several of us came away from a lap around the road course wearing wide smiles.

The Mini Cooper D gets impressive fuel economy (rated at 60 mpg combined on the European fuel economy test cycle). The Cooper D driven at Pocono didn’t require as much shifting as our base Mini Cooper with a manual transmission to stay in the power band, but it had a notably gruff engine sound. The same was true for the torquey and entertaining BMW 123d hatchback, which was rated at 45 mpg overall. Both the Mini and the BMW included an auto-stop feature that shut the engine off when the car was stopped to avoid wasting fuel when idling.

Bosch tells us the Chrysler 300D uses the same 3.0-liter V6 diesel engine as the Mercedes we tested. It was plenty powerful in the Chrysler, but not as smooth as in the Mercedes. (Also, we smelled diesel fumes after making a U-turn, whereas we couldn’t smell a thing in the Mercedes, even with our nose near the tailpipe while it was idling.) It’s rated at 35 mpg overall.

In the end, the lesson is that while modern technology has dramatically reduced diesel vibration and sluggishness, they aren’t as smooth as the best gas engines. Powertrain noise and vibration suppression are a combination of engine design, noise reduction under hood, and engine mounting technology. Nevertheless, the sacrifices to drive a diesel are much smaller than they once were, making the fuel economy improvements and abundant torque all the more compelling.

Now if only diesel fuel prices were closer to regular gasoline…

—Eric Evarts

Comments

[david]

How feasible would it be to have a rotary powered diesel car? The Mazda RX-8 has a great engine. Three complaints have been lack of low-end torque, low gas mileage, and need to check engine oil often. Diesel provides lots of torque. Diesel gets better mileage than gasoline. Diesel acts as natural lubricant. However, will the rotary still be able to spin at 9,000rpm? I say it is worth exploring.

[Susan in Reston, VA]

This is great news! In 2005 we took a large family vacation around Barcelona and rented several small diesel-engine cars. We were amazed by the fuel economy in cars that were essentially American cars sold under Euro names (one had to be a Pontiac Vibe sold by Renault). Being on vacation, not on the Autobahn, and moving from one small Euro town to another, we never pushed the performance limits. But these cars did everything we asked and we only worried that the fuel gauges might not be working as they did not seem to drop.

[Stuart]

Now how about putting two good technologies together and making a diesel hybrid?! It is also worth mentioning that diesels have a reputation for lasting longer than gasoline engines and requiring less maintenance.

[Jeff Bartlett - Consumer Reports]

Concept vehicles that have combined hybrid technology with diesel engines for impressive mpg claims. However, each technology adds significant cost over a traditional gasoline engine. Combining them would be expensive.

[Eric]

Are the mpg ratings using US or imperial sized gallons ?

[Greg Hunicutt]

Regarding diesel/electric hybrids, I believe I read a year or so ago about Mercedes offering such a vehicle, or at least testing one, for their S series, which is of course their high(est)-end sedan model. And I may have read the same about Audi offering one for their largest SUV (can't keep up with their letter/number nomenclature).

[Greg]

Why is Diesel so much more than regular? Does not make since, it use to be cheaper than regular. How can it cost more now?

[44 mpg by 2010]

Currently gasoline prices here in NC are about $3.90/gallon(US) and diesel is generally within +/- $0.18/gallon. I have seen diesel $0.15 BELOW gasoline at several stations over the past week.

[K]

In the US, diesel has the disadvantage of being taxed at a slightly higher rate, which probably accounts for about $.05 - $.10 of the additional cost.

I for one would love to have a diesel vehicle, the problem is that so many of the diesel vehicles are the luxury class Mercedes vehicles or large trucks. The VW Jetta Sportwagon is particularly appealing.

It's interesting though that there are so many more fuel-sipping vehicle options in Europe. There are not only more models of vehicles, but smaller engine options of the same models sold in the US. Is this because Americans simply choose not to buy the smaller engine models, or do manufacturers avoid selling and producing lower priced configurations of vehicles in the US to force us to buy higher profit margin products? Just check out www.ford.co.uk where you can configure several vehicles that will do over 40mpg on regular gasoline. Why are we having to buy expensive hybrid vehicles to get similar fuel consumption?

[everett whitney]

TO: Stuart - 19 Sept -"Diesels have lower maintenance..?"

Not the case at all in these newest versions about to come to market!

Re-read here the article / testing by C.R. of the Mercedes
Bluetec 320 engine ..... Urea Injection, particulate filters, etc., in order to pass EPA stipulations here! Much different than in Europe.

The periodic replacement / servicing of these by a certified Tech @ $90/hour + the costs for those materials, shop charges, so on WILL definitely consume much of the financial benefits of 30-35 mpg!

[bob ackley]

diesel fuel prices in Europe (or at least Germany where i currently reside) are around $0.75/gal less than regular fuel: that equates to about $8.15/gal for diesel fuel. so why doesn't everyone in Europe drive a diesel given the lower fuel cost? because diesel-powered vehicles are taxed (yes, must pay annual tax on your vehicle) much higher than non-diesel vehicles, essentially eliminating the advantage for most. one basically has to drive a lot of miles each year in order to offset the high vehicle tax cost.

[Chris Sanders]

I'm told that Diesel does not have to go through the amount of processing that it takes to refine gas and is therefore less expensive to refine.
The fact that it is at a higher price than gas right now is that our 160-some refineries ( half of what we had in the 70's ) have to switch between refining one from the other through demand. In other words, they can only make one or the other at a time and they only make what they absolutely need to in keeping demand high as the oil companies no longer own them...they are privately owned now while Congress refuses to build more due to tree-hugger activism.

If these engines are everything our guys say they are then we could switch very easily and cut our oil demand in half nationwide.

Very interesting and compelling idea.

[michaelfrankie]

Writing this from Krakow Poland on vacation. Just saw a Subaru Legacy with the boxer Diesel engine. I think this is a match made in heaven.

[Happy]

I have been driving a 1998 VW Beetle with a 90hp diesel in it. I now have 205K miles on it and have never recieved less than 53 mpg. When brand new it was at over 60 mpg. Everytime I pass a hybrid I have to laugh.

Diesel engines are the way to go, no smog check requirment, no tune ups, just change the oil and go.

It is a shame we American's as so stupid when it comes to appling today's technology to today's problems.

RD

[Paul]

RE: David's question on a Rotary diesel - My understanding is that it is not possible to have a rotary diesel. The energy from diesel is caused by compression ignition. A rotary engine does not provide the compression needed to ignite diesel fuel. Since gas is ignited with a spark plug instead of compression, rotary engines work fine (albeit inefficiently) with gas.

[Alan Cavin]

The same 3.0 L diesel in the Chrysler 300 is in the Jeep Grand Cherokee. In your review of the 2008 Laredo you indicated that the diesel was being discontinued. However, several sites I've looked at indicate its availability through 2010. Even with higher diesel prices, the significantly better mileage makes this a good SUV pick, especially for someone who tows an travel trailer. So, what is the story on the JGC diesel?

[Bill]

As the proud owner of two 2000 Jetta TDI's and one 1978 Mercedes 300CD I can tell you I'm familiar with the way diesel technology has changed over the years.

It's a shame that those in power (read, both our government leaders and those working in Detroit) have this built in perception of "what American's want". If you give them more options, they have the ability learn and expand their choices.

Detroit seems to feel that we all still want v-8 muscle cars, hence all of the 'retro' style cars that they are producing.

Our leaders seem to feel that we need to be protected and use 'safety' as the excuse of not pushing for efficiency improvements.

Meanwhile, their perceptions are driving the middle class right into the poorhouse!

Overall it was a decent article, thank you, however your last line pretty much shows the same ignorance that the American public has about diesel fuel prices and math. Two cars have a 15 gallon fuel tank, 1 car gets 30mpg and the other 45mpg. Assuming Unleaded is $3.50/gallon and Diesel $4.00/gallon, I pay $9 more but I can go an extra 225 miles on the same quantity of fuel.

[gmcinva]

I have leased a 2008 Mercedes-Benz ML320CDI for one year now. It averages 21 mpg in town and 26 mpg in highway driving. It only has 11,500 miles on it, but has required only an oil change and tire rotation during the first year. It is considerably more powerful in acceleration and towing capacity given the higher torque of the diesel compared to gasoline engines. The low sulfur diesel fuel has a cost penalty of approximately $0.30 per gallon here in Georgia, due to higher taxes and refinery capacity limitations. Nevertheless, it is still more economical than gasoline or hybrid engines in comparably sized vehicles. I leased the vehicle because I wasn't sure about the longer term aspects of owning the diesel SUV, but as of now I would buy it when the lease term is up if current performance continues.

[Dan]

The first diesel was designed to run on peanut oil. Then, the oil companies got involved...