Video: Diesel comparison - BMW, Mercedes-Benz, Volkswagen

For buyers looking for a fuel efficient car, diesels provide an alternative to hybrids. Popular in Europe for years, more diesels are making their way to the U.S. market.

Modern diesels escape many of the liabilities of earlier designs. They are quieter, burn cleaner, and have much improved acceleration. Fuel economy is considerably improved over gasoline-powered versions.

But buying a diesel usually means paying more up front. Finding a diesel pump isn't quite as easy as locating gasoline, and diesel fuel prices recently have fluctuated widely. Except for Volkswagen, diesel vehicle availability is also limited to high-price luxury brands.

In this video, we take a look at four diesels—Mercedes-Benz GL320 Bluetec, BMW 335d, BMW X5, and the Volkswagen Jetta TDI—and their pros and cons.

—Tom Mutchler

2009 Annual Auto Reliability Survey: Best and worst models by car maker

It is easy to assume that certain automakers build only reliable cars and others don’t, however, nearly every manufacturer have their share of winners and losers in our annual reliability survey. Each company and even brand product portfolio runs a spectrum of reliability performance, with its own best and worst examples. For some, the range can span from much better than average to much worse than average, whereas other may be centered around average. The key lesson from scanning the data within an automaker is not to make assumptions.

For example, the best Toyota Motor Company model in our reliability survey is the Lexus SC—its predicted reliability score is the second highest out of over 300 vehicles, but the worst is the Lexus GS (AWD), which scores in the bottom 10 percent, and receives a much worse than average rating, and is not recommended in our testing. While it is true that Lexus models tend to be reliable and test well, this is not the case for all Lexus vehicles.

The greatest disparity comes from Volkswagen. The VW Golf (aka Rabbit) is one of the most reliable small cars you can buy, but the Volkswagen Touareg has the lowest predicted reliability score in our 2009 Annual Auto Survey.

In most cases, the best model for reliability is a recommended model and the worst is not. However, Honda’s top reliable vehicle in our survey, the Honda Insight, is not recommended due to low scores in our testing. The least reliable Honda vehicle is the Acura RL, but it has an average reliability score and is recommended. Honda is one of the more consistent manufacturers and has no model that scored below average in reliability.

The two more reliable General Motors products are from two brands that are leaving the GM umbrella. The Saturn Aura (4-cyl.) is newly recommended this year and the Pontiac Vibe will be phased out in the coming months.

Below are the best and worst models in reliability. Models with an * are based on data of one model year only.

BMW
Best: BMW 328i (RWD)
Worst: BMW 535i (AWD)*

Chrysler
Best: Jeep Patriot
Worst: Chrysler Town & Country/Dodge Grand Caravan

Ford
Best: Ford Fusion/Mercury Milan (4-cyl.)
Worst: Ford F-250 (turbodiesel, 4WD)*

General Motors
Best: Chevrolet Malibu (V6)
Worst: Chevrolet Colorado/GMC Canyon (4WD)

Honda
Best: Honda Insight*
Worst: Acura RL

Hyundai/Kia
Best: Hyundai Tucson
Worst: Kia Sedona

Mazda
Best: Mazda3 sedan
Worst: Mazda CX-7

Mercedes-Benz
Best: Mercedes-Benz GLK*
Worst: Mercedes-Benz GL-Class (turbodiesel)*

Nissan
Best: Infiniti M35 (RWD)
Worst: Nissan Versa sedan*

Subaru
Best: Subaru Impreza Outback Sport
Worst: Subaru Impreza WRX*

Toyota
Best: Lexus SC*
Worst: Lexus GS (AWD)

Volkswagen
Best: Volkswagen Golf (Rabbit)
Worst: Volkswagen Touareg*

Volvo
Best: Volvo S40 (FWD)*
Worst: Volvo XC90 (V8)*

The main take away from this information is don’t judge a book by its cover. Avoid assumptions and do your research before you buy your next vehicle. It takes just a few minutes to browse the model overview pages, or use the interactive new car selector tool, which sorts and filters by the parameters that matter most to you.

Either path will reveal Consumer Reports recommended models that did well in our road tests, score average or better in reliability, and performs at least adequately if included in government or insurance industry safety tests.

For more details on our 2009 Annual Auto Survey including the full list of most and least reliable new cars by vehicle type, see our reliability report. Also, check out our guide to car reliability for more details on new and used car reliability as well as owner satisfaction.

—Liza Barth 

From the logbook: 2010 Mercedes-Benz E350

Some cars simply are tough acts to follow. Take the last-generation Mercedes-Benz E-Class. This midsized luxury sedan set benchmarks in its class for steering and ride. It was quiet, comfortable, and quick. Complicated controls and a checkered reliability history--until its final years--counted against it.

So Mercedes-Benz faced a challenge when they redesigned the E-Class for 2010. To find out if they measured up to the task, we bought one to test. Our E350 came, like most rear-wheel-drive E-Classes sold around here, with the sports package, adding a sports suspension, some lower body cladding, and all-season 18-inch tires. Snazzy AMG wheels, a Premium Package with navigation and harman/kardon stereo, and a panorama sunroof brought the total to $55,245.

How is the car to drive? Let’s check the initial feedback from our testers by cracking open the car’s logbook:

“Quick, linear steering but has very low effort.”

“Silly shifter easily confused for right stalk. Started to rain and I instinctively pushed it up for wiper – went into neutral on highway.”

“Once again, a redesign comes out and I prefer the previous-generation car.”

“Steering here is too light and short on feedback, despite tons of grip and great body control.”

“NAV is frustrating to use, even by voice.”

“Not fond of the seatbelt power snugger trying to choke me.”

“Powertrain is very smooth and pulls great on highway for passing.”

“Back-up camera only works if audio system is on.”

“Car has an ‘avant-garde’ feeling to it”

“Steady as a rock long distance cruiser. Quiet.”

“Center control thing can be confusing at first but handy for moving between presets.”

“Fit and finish is superb.”

“This E-Class leaves me completely cold. Overly contrived styling, inside and out.”

“Ride is a bit stiff-legged.”

“I like the old one better. More impact harshness and noise now.”

“Strong and quiet powertrain.”

“Gets lots of looks and favorable comments.”

“Still engaged cruise control rather than turn signal three times.”

“Somehow it’s not quite the same as the previous generation.”

To sum up, the new E350 is eye-catching, especially given that the last E-Class grew familiar as it remained essentially unchanged for seven model years. But some faults--particularly complicated controls--remain. Perhaps more troubling, the E350 doesn’t drive like the old one, and given how good that car was, that’s a big disappointment.

—Tom Mutchler

Test complete: 2010 Mercedes-Benz GLK350

Based on the C-Class sedan, we had high hopes for the Mercedes-Benz GLK. Mercedes sedans have a well-earned reputation for delivering an excellent, composed ride and agile handling. With the standard 3.5-liter V6 and seven-speed transmission, it appeared on the scene as a promising new competitor in the ever-growing luxury small SUV class.

Unfortunately, it doesn’t achieve its potential. The steering isn’t very responsive and the ride suffers from too much side-to-side rocking at low speeds. A cramped rear seat with narrow door openings and a wide expanse of a doorsill compromises utility. The refined powertrain does provide plenty of motivation, but the 18 mpg overall on premium fuel is less than you would get in a much roomier and better mannered Lexus RX350.

Overall, much like some others in this class - it’s difficult to find many reasons to pay the $41,760 sticker in our test car over a loaded Toyota RAV4 V6 or a turbocharged Subaru Forester. Both can be equipped with leather, offer comfortable rides, are more agile to drive, and cost around $10,000 less. Then again, they don’t have the coveted Mercedes Tri-star logo, nor distinctive Lego-block styling and golf-club cachet.

Learn more about the Mercedes-Benz GLK350, with road tests, pricing, and more, in the model overview (available to online subscribers).

—Liza Barth and Jake Fisher

Diesel power just in: Mercedes GL320, BMW X5 3.0 diesel, BMW 335d

Some automakers have had long-standing plans to offer diesel engines in this country. European automakers have stuck with those strategies despite the volatile price disparity between diesel and regular fuel. Japanese and domestic automakers, including Honda, Nissan and GM, have shelved their diesel plans for now.

Impressed by diesels we’ve previously tested from Mercedes-Benz and Volkswagen, we have added three more to our test fleet to see how they compare to their conventional counterparts. Our latest diesel models include the Mercedes-Benz GL320 Blue Tec and a pair of BMWs--the X5 and the 335d.

Mercedes-Benz GL320 Blue Tec
We were impressed with the GL450 when we tested it in 2006--a roomy, comfortable, yet responsive handling vehicle. We were also impressed with the 210-hp, 3.0-liter V6 diesel engine when we tested it in the E320 Blue Tec, which combined strong performance and refinement, yet returned 29 mpg overall. It was also free of traditional diesel smell, smoke, and sluggishness. Hence, we wanted to see how this engine performed in the GL.

Even though the GL is very heavy (5,655 lbs.), this engine remains smooth and muted, but initial off-the-line acceleration is sluggish. Once underway, it pulls strongly and manages to hit 60 mph in less than 10 seconds--a far cry from the 7.4 seconds we recorded for the GL450. Observed fuel economy, so far, is averaging 20 mpg overall. We got 15 mpg for our V8-powered GL450. If you’re starting to crunch the numbers, you should know that the GL320 is actually $1,000 cheaper than the GL450.

The other major difference between the two is that the GL320 comes with 20-inch run-flat tires, which brings more impact-harshness to the ride quality. Plus, the steering feedback is compromised. The GL benefits from a $1,550 federal tax credit for the first 60,000 purchasers, but you won’t qualify if you hit the AMT tax.

BMW X5 3.0 diesel
In contrast to the Mercedes example above, the X5 diesel adds an eye-opening $3,700 to the price of the 265-hp, regular-gas 3.0 model. So far, our diesel X5 is getting 23 mpg on average, compared with 17 mpg overall for the gas version. The X5’s diesel is not quite as refined as the Mercedes but feels punchier. In fact, it beats the regular X5 in 0-60 mph acceleration, but it’s less quick initially from a standstill. Other than that, the diesel X5 retains the choppy ride, excellent steering and agile handling (as well as confusing controls) of the standard X5.

Diesel and gasoline are about equal in price these days, so it’s a matter of how far you drive when it comes to payback time for the diesel version’s higher price. There is also added maintenance due to the replacement of the Urea solution (also required with the Mercedes), which serves in emission-cleaning arsenal. BMW replaces it at service intervals and will warn you 1,000 miles prior. This diesel qualifies for a $1,550 federal tax credit. With that, and at current gas prices, and with an annual mileage of 12,000 miles it would take more than four years to break even.

BMW 335d
On the face of it, there is a $2,275 premium for a 335d over the rear-wheel drive 335i, once adjusted for the standard automatic transmission in the diesel. However, assuming your attitude is one of saving money and fuel, you’d probably look at the more popular 328i. In that case, the diesel commands a whopping $8,975 price premium. So far we’ve been getting 33 mpg with the diesel according to the car’s trip computer. Our last 328i attained 23 mpg overall.

Beyond the questionable economics, the diesel 3 retains its excellent steering and body control and one might argue is even more of a hoot to drive. We haven’t completed our acceleration tests yet, but the torque of the diesel delivers an addicting mid-range rush that, if you’re not careful, will send the car into three-digit speeds all too easily. The 335d benefits from a $900 federal tax credit. With that taken into account it would take about 20 years to break even compared to a 328i at an annual mileage of 12,000.

Bottom line
In general, diesel engines cut fuel consumption by about 30 percent and as a byproduct reduces C02 emissions. And contemporary common-rail diesel combined with devices that abolish smoke and smell make the engines a lot more livable. That said, in terms of particles causing soot, diesels are still not as clean as modern gas engines.

Opting for a diesel in today’s environment may not save you money. It is a function of the price differential to the conventional version, the price of diesel fuel and your annual mileage. Other than economics, any diesel can be fueled with an up to 20 percent bio-diesel blend, which further cuts petroleum consumption. If diesel prices remain similar to gasoline, as they are today, there would be true appeal.

—Gabe Shenhar

Car brands: Who owns what?

The auto industry is very complicated these days, with constant change across all corners of the globe. The worldwide economic slowdown dictates widespread cost reductions, inspiring partnerships and changes in ownership. Further confusing the scene are past commitments between companies: For example, the new 2011 Jeep Grand Cherokee is based on a Mercedes-Benz platform–even though Chrysler and Mercedes are no longer joined at the hip.

To help clear up some of the confusion, here is a road map to navigate who owns what brands among the major companies that sell in the U.S. car market.

BMW owns: BMW, Mini, and Rolls Royce

Fiat owns: Alfa Romeo, Ferrari, Fiat, Lancia, Maserati; Chrysler, Dodge, Jeep–20-percent stake

Ford Motor Company owns: Ford, Lincoln, Mercury, Volvo (for now), and still owns 13.4 percent of Mazda

General Motors owns: Buick, Cadillac, Chevrolet, GMC. Also owns a controlling interest in Daewoo, as well as Opel and Vauxhall in Europe and Holden in Australia. (Pontiac to be discontinued)

Honda owns: Honda, Acura

Hyundai owns: Hyundai, Kia

Tata Motors (India) owns: Jaguar and Land Rover

Mazda (partially owned by Ford)

Mitsubishi

Daimler AG owns: Mercedes-Benz and Smart

Nissan owns: Nissan and Infiniti (Nissan is owned by Renault--France)

Porsche owns: Porsche and a majority share in Volkswagen

Subaru (A controlling interest of Subaru is owned by Toyota)

Suzuki

Toyota Motor Company owns: Lexus, Toyota, Scion, Daihatsu and Hino Motors, with a stake in Fuji Industries (Subaru’s parent company) and Isuzu

Volkswagen owns: Audi, Volkswagen, Bentley, Bugatti, Lamborghini, and overseas SEAT and Skoda.

In formal negotiations to be sold:
Hummer: Tengzhong (China)
Saturn: Penske Automotive Group
Saab: Koenigsegg (Sweden)

--Liza Barth

2009 New York Auto Show: Mercedes is not asleep at the wheel

Mercedes-Benz’s new Attention Assist drowsiness detection system will be available in its new E-Class. According to the company, the system “has a highly sensitive feel for its driver’s attentiveness, and warns him of drowsiness ahead of time… [and] is equipped with highly sensitive sensors that continuously monitor more than 70 different parameters.” As a 20-year auto show veteran, I’d like to see this equipment issued at some of the press conferences. After some of the speeches I’ve heard over the years, I’d appreciate anything that would keep me from nodding off--especially this year, with announcements being less dramatic and arguably significant than in years past. So far, the vat of Starbucks I’ve already consumed is doing the job, and we’re on the trail for several interesting stories.

Mercedes’ system comes with “audible warning accompanied by a visual warning in the instrument cluster.” Maybe all the seats at the press conferences could come with wires to shock people awake. No word yet if the system works with the car’s GPS to take you straight to Dunkin’ Donuts or your caffeine dream of choice.

--Mike Quincy

See Consumer Reports' coverage of the 2009 New York auto show.

2010 Mercedes-Benz E-Class coupe

Designed as a replacement for the CLK-Class, the 2010 E-Class coupe is a sportier version of the new E-Class sedan. It will feature the same engine choices--a V6 producing 268-hp (E350) or a V8 producing 382-hp (E550). Both engines are mated to a seven-speed automatic transmission and configured as rear-wheel drive. Fuel economy estimates are not yet available.

The design is a classic coupe profile that features fully retractable side windows. Mercedes claims this new coupe will be the most aerodynamic production vehicle in the world with a drag coefficient of 0.24 (the sedan is 0.26). This beats Toyota’s claims for the 2010 Toyota Prius at a drag value of 0.25.

A number of safety and technology advances will be available including an active suspension with adaptive shock absorbers, drowsiness detection, and adaptive high beam assist.

More details on the U.S. model will be revealed at the New York Auto Show in April. It will hit dealerships in June 2009. The E-Class convertible is expected to arrive in the U.S. in early 2010.

--Liza Barth

Car brand perception vs reality

Automakers spend billions annually to shape public perception for their products and brands, and in 2008 they were aiming at a moving target. During the past year, gas prices soared past $4 a gallon, then plummeted below $2; the economy put jobs and household budgets in peril; and the finance crunch made it more difficult to lease a car or secure a loan. Consumers held off on new-car purchases and placed a greater emphasis on factors that impact the wallet.

Perception
The latest Auto Pulse survey conducted by the Consumer Reports National Research Center focused on how consumers perceive and rank car brands in seven crucial areas, including safety, quality, value, performance, environmental friendliness, design, and technological innovation. It also looked at which of those factors are most important to consumers when buying a vehicle.

As expected, we saw rankings shift in the 2009 Consumer Reports Car Brand Perceptions Survey compared to last year’s results. Toyota and Honda again top the list for over all score, leading by significant margins. However, domestic brands Chevrolet, Dodge, and Ford saw decreases in overall brand perception.

To rank the brands, the Consumer Reports National Research Center conducted a random, nationwide telephone survey, interviewing 1,745 adults whose household owns at least one car. From this, an overall brand perception index was calculated based on the total number of times that the particular make was mentioned as an exemplar in any of the seven categories.

Brand perception – Top 10
Toyota – 193
Honda – 149
Ford – 109
Cadillac – 102
Mercedes-Benz – 100
GMC – 98
Lexus – 95
BMW – 95
Chevrolet – 94
Volvo – 88

Reality
Now, this is not to say these are the "best" brands. Such a statement would warrant much more critical analysis than a perception survey, though ConsumerReports.org provides exhaustive information to help in making such assessments based on your own priorities. Going through our New Car Selector, you can filter and sort based on the factors that matter most to you, such as reliability, safety, owner costs, and road test scores.

In scanning through the brands highlighted here, you find invariably that each offers a range of models that perform across a spectrum. While it may be possible to make some general statements, it is more difficult to match the perception of good cars overall with matching test and survey results. For instance, BMW and Mercedes models tend to do well in our tests, however there is significant variance in reliability.

Perception doesn’t always match reality, though such surveys can provide an interesting mirror to the world and reveal trends.

See our full report on the 2009 Consumer Reports Car Brand Perceptions Survey for results in all seven categories and insights into what they mean.

—Jeff Bartlett

Clean diesel engines coming to a road, and track, near you

lean diesel technology is beginning to take root. Friday at our "Future of the Car" event I drove a couple of clean diesel SUVs, an Audi Q7 and a Mercedes-Benz ML320D. In both, the powertrains were very impressive: quiet, smooth, powerful, and quick. The Q7 is a stretched cousin of the Volkswagen Touareg while the ML320D is a diesel version of the familiar ML.

Since these were just trial laps around our swoopy mile-long ride evaluation course, and not instrumented runs, I can’t tell you what the timed acceleration numbers would be. By the seat-of-the-pants feel, these SUVs felt good, and if you weren’t told, you wouldn’t guess these were diesel engines. They felt punchy and responsive and there was no clatter, no smell, and no slow-motion takeoff. They will soon be joined on American roads by diesel versions of the Mercedes R320, GL320 (with the new Bluetec technology) SUVs, and the BMW 335 and X5. The Volkswagen Jetta diesel is already available.

It’s hard to overstate the potential significance of clean-diesel technology. The superior thermal efficiency of a diesel engine promises about 30 percent more miles per gallon than an equivalent gasoline engine, right from the get-go. If a big chunk of the current American fleet switched over to diesel, the cumulative fuel-savings would be gigantic. Essentially, it would cut fuel demand by one third without sacrificing space, power, or utility. The Audi and Mercedes-Benz reps who brought these vehicles to our test track told us that the cruising range of each was about 600 miles on a  tank.

The arrival of these first few clean diesels coincides with a milestone in air-quality standards, as well. Next year marks the completion of a phase-in period when all passenger vehicles -- both cars and light trucks, gasoline or diesel powered -- must meet the same stringent emissions standards, technically known as Tier 2 regulations. The rules put strict limits on smog-forming or otherwise toxic emissions, including carbon monoxide, non-methane organic gases, hydrocarbons, and particulate matter.

Particulate matter, or soot, has been a special concern with diesels, since fine particulates have been linked to lung disease. The Tier 2 standards reduce allowable particulate matter emissions to zero.

The other emissions hurdle that diesels have had to overcome to make the grade here is on oxides of nitrogen, or NOx emissions. NOx is one of the smog-forming pollutants. Engines that run lean, meaning they run using lots of air and relatively little fuel, tend to create lots of NOx just as a result of combusting the oxygen portion of atmospheric air and the chemical reaction that creates. Part of the Bluetec system jointly developed and used by Mercedes-Benz, BMW, Chrysler, and Volkswagen/Audi have a special method for dealing with NOx emissions.

Some vehicles will use a urea-injection system that combines with catalytic action to filter out NOx, while others, such as the Jetta, use a soot and NOx trap that is periodically flushed by running the engine a little rich and catalytically burning the accumulated soot.

This technology enables the smooth, powerful diesel powertrains like those sampled at the test track. But could diesels go even further to improve vehicle fuel economy? I’ll explore that in my next blog.

—Gordon Hard