The Difference with Today's Diesel
If you were travelling the roadways of America in the early '80s, you might recall the occasional encounter with diesel engines in vehicles other than 18-wheelers and construction trucks. I remember my first time, hearing what I thought was a large truck idling beside me at a red light. It would be an understatement to say I was surprised to see an innocent-looking passenger car making all that noise - a Mercedes-Benz 300.
It wasn't long before I started noticing diesel-powered passenger vehicles all over town. They were unmistakable with their loud, hammering engines and exhaust filled with black smoke and unusual (but unmistakable) odor. At the time, I didn't get the attraction. These polluters didn't appeal to me at all, and I quickly dismissed them as a passing fad.
Flash forward to last week, when I was handed the keys to our long-term test vehicle, a 2011 Volkswagen Jetta TDI that we affectionately refer to as Olga. She's a 2.0-liter 4-cylinder turbo diesel-powered cutie, and I've spent the last week getting acquainted with her modern diesel engine. I have to say, all things considered, I'm now a fan.
Like its predecessors, this diesel engine is really efficient. With a 42-MPG highway rating, the Jetta's trips to the fuel pump are refreshingly few and far between. Unlike its predecessors, which were known to exhibit frustrating "turbo lag," this car is immediately quick when the accelerator is pressed with intent. Despite its four doors and spacious cabin, it feels a bit like a sports car in terms of response and handling.
Another improvement (and a drastic one at that) is in the area of emissions, which is to say there are virtually none. Gone are the smoke, the soot, and the smell, thanks in large part to the addition of common rail fuel injection technology, which optimizes the engine's efficiency. The Jetta also benefits from not needing the urea exhaust cleaners required for larger diesel engines. The urea fluid in those engines must replaced regularly, which typically means higher maintenance costs.
And let's talk about fuel for a minute. Back in the day, diesel-powered cars ran on comparatively dirty diesel fuel. It was cheap, and certainly plentiful. But it was dirty, hence the aforementioned telltale exhaust issues. The upshot for diesel pioneers, however, was that their cars could run on pretty much anything that would burn. It was commonplace for diesel drivers to use things like brake fluid and power steering fluid to keep their cars hammering and knocking along, especially if they were in a pinch to make it to the next filling station.
Outside of a truck stop, the diesel fuel sold at most stations today is of the low-sulfur variety. Gone are the days when there was a significant cost savings, as low-sulfur diesel costs about the same as premium gasoline. But it's noticeably easier on the eyes and nose, if not the wallet.
Lastly, I would be remiss if I failed to mention the new and improved sound. Regarding the Jetta TDI, Volkswagen claims that, "The engine runs nearly as quietly as a gasoline engine...," a statement with which I respectfully disagree. With another tip of the hat to modern diesel's many technological improvements, the Jetta TDI is markedly quieter than was, for example, a 1980s-era diesel VW Rabbit or that old Mercedes I met years ago. But when I press Olga's "Start" button, there is the mild but distinct "hammering" sound that has always been the signature of these engines.
When I hear it, I immediately think, 'that sounds like a diesel' - and I like it.