Shortly prior to publishing the treatise that would become the foundation for the engine that would bear his name, Rudolph Diesel was actually working on a steam engine that ran on ammonia vapour. Fortunately for us (and semi-unfortunately for Herr Diesel), the thing quite literally blew up in his face, sending Rudolph to the hospital.
Perhaps if he'd got that crazy contraption to work, he might never have been spurred to invent the robust, torquey, long-lived and highly efficient powerplants that now power everything from submarines to passenger-aircraft. But he did, and today we don't have to fill our Jettas up with ammonia vapour, which is probably a good thing.
As the price of fuel has steadily increased over the years, the popularity of diesel technology has enjoyed a resurgence in popularity. What's more, the modern diesel is a far cry from the stinky, smoke-spewing early imports that once blighted our roads with their tortoise-like slowness.
In fact, clean, efficient and powerful non-commercial diesel passenger cars are available from almost every manufacturer. Here in Canada, we might not get every model yet, but there are more diesel-equipped models available this year than any other.
MERCEDES BENZ
It seems fitting to start with Mercedes-Benz. It could be argued that their 260D was the first proper diesel-equipped passenger car to go into production. They also pioneered the turbodiesel in the late '70s, and many of those early M-B sedans are still on the road today, a testament to their longevity.
Mercedes offers five models with its Bluetec-branded diesel technology, all using the same engine. It's a 3.0L turbocharged V6 producing 210hp at 3400 rpm and 400lb/ft of torque from 16002400rpm. This chunky low-end pulling power is characteristic of all diesels engines.
What's new to BlueTec is the addition of an additive system that injects urea into the exhaust stream. Dubbed adBlue, this nontoxic solution reacts with the nitrogen oxide compounds in the exhaust stream to form nitrogen and oxygen. It's considerably cleaner than standard diesel exhaust, but be aware that it adds an additional cost to operating your vehicle.
Again, the 3.0L V6 is available in a range of Mercedes, starting with the E350 BlueTec mid-size luxury sedan. Here it is in its most efficient form, with highway fuel consumption of 5.9L/100kms, roughly equivalent to a sub-compact like a Nissan Versa.
Mercedes also offers their flagship S-Class in a diesel, the only full-size executive sedan available with these efficiency levels. The van-like R-Class, while ungainly in appearance, also provides an enormous amount of utility.
Two SUVs round out the range, with the 5-seat ML being the most popular. For those who need maximum capacity, the GL 350BlueTec is easily the largest in the full-size luxury class, besting the Audi Q7 by virtue of the more squared-off design of the Mercedes.
BMW
Arch-rival to Mercedes-Benz, BMW's 3.5L turbodiesel engine is strikingly similar in concept: a 3.0L turbocharged V6 with adBlue injection for cleaner running. However, there's a difference.
As you might expect, BMW's single diesel offering-the redesigned 3-series no longer has a diesel option-is sportier than the competition. With 265 hp and 425lb/ft of torque, it can sprint to 100 km/h in under seven seconds; extremely impressive for a full-size SUV.
Naturally, there are some compromises. With a highway fueleconomy of 7.6L/100kms, the X5 is pipped by the similarly sized ML which will do 6.8L/100kms. What's more, the X5's sportiness extends to the ride as well as the handling. It can be considerably more firm than its Teutonic competition.
The real shame here is that BMW hasn't really embraced diesel technology fully for the North American Market. Compare their single SUV to the full range of diesels available in Europe and note especially the new range of M-Sport diesels that are currently offered on the other side of the pond. For those thinking that diesel is any less of a performance engine than gasoline options, you should note that M versions of the diesel 5-series, X5 and X6 are all capable of sprinting to 100km/ h within tenths-of-a-second of the mighty twin-turbo M5.
Volkswagen
Apart from the luxury marques, the people's car-company is the lone company producing diesel engines for the rest of us. What's more, they've been at it for years.
There are currently five different models available with Volkswagen's Turbocharged Direct Injection (TDI) technology. The passenger cars all utilize a 2.0L engine producing 140hp at 4,000 rpms and 256 lb/ft of torque low in the rev range from 1,750-2,500 rpm.
On the smaller side, we have the Jetta, five-door Golf Hatchback and Golf Wagon. Each is available with either a 6-speed manual transmission, or VW's quick-shifting dual-synchronousgearbox. For maximum fuel-economy, the manual transmission still can't be beat: all three are rated for 4.6L/100km on the highway, which should net you more than 1,000 kms per fill-up.
One particularly nice thing about a small diesel Volkswagen -and one that you might not find with other models-is that Natural Resource Canada's very optimistic fuel economy ratings are often actually attainable, and you needn't employ all your hyper-miling tips n' trucks. Personal choice will govern whether the sedan, hatchback or cargo-haulin' wagon will fit your lifestyle best.
For those needing slightly more space, Volkswagen offers the Passat mid-size sedan and the Touareg full-size SUV. Both are available with the adBlue additive to reduce emissions even further.
The Passat has grown into a spacious and handsome vehicle, and is a far cry from the early Passats with their somewhat spotty reliability.
Even more so than the Jetta TDI, a diesel version of a Passat will sit headand-shoulders above other trim-levels in terms of resale value.
The Touareg TDI is this year's AutomobileJournalists Association of Canada (AJAC) utility vehicle of the year, rightly praised for its roomy interior and conservative-but-handsome styling. Better yet is the 3.0L V6 that is the heart of the beast: it produces 225hp and 406lb/ft of torque while achieving 8L/100kms fuel economy on the highway.
Audi
Being so closely partnered with VW, it should come as no surprise that Audi's diesel offerings are almost exactly the same in power output and design. Two models are available, a TDI version of the A3 that is essentially a more luxurious Golf 5-door, and the Q7 TDI.
The Q7 is a best-seller, and has been so for some time. Adding in the efficiency of diesel just makes sense for Audi's family hauler, based as it is on the Touareg chassis. While, as mentioned, the Audi lacks the cavernous capacity of the GL, it is a considerably smaller-feeling rig, and still larger in terms of rear passenger space than sevenseater versions of the X5.
Mazda
While there are several automakers that sell Euroonly diesels, it is worthwhile to single out Mazda as they will likely be next to bring a diesel-equipped vehicle into the US market. Moreover, Mazda's diesels are different enough from the more conventional competition to warrant mention.
The weight-saving portion of Skyactiv technologies has been well advertised, but part of Mazda's strategy is also streamlining the production of their engines. The result is very high-compression gasoline engines and quite low-compression diesel engines.
Low-compression diesel seems counter-intuitive, given that the pressure is what ignites the fuel-air mixture. However, Mazda's design allows for a more even fuel-air mixture (which burns cleaner) and for a lighter rotating mass (which allows the engine to rev more quickly).
The Skyactiv-D engine, as it is dubbed, is expected to show up in 2013 and, in all likelihood will be available in the new Mazda6 sedan, and possibly the new CX-5 cross over. Having driven it in prototype form, I'd say it can't get here soon enough.
[email protected]. Twitter: @brendan_mcaleer
