Why it’s still not that easy to find diesel fuel

The age of diesel seems to be coming back. Lately, we’ve driven a lot of great diesel cars, SUVs, and trucks, from the top-scoring Mercedes-Benz E250 Bluetec to the ½-ton Ram 1500 pickup. Likewise, the U.S. Census Bureau reports that the percentage of gas stations selling diesel went up from about 35 percent in 1997 to more than half in 2007. Yet our experience shows it hasn’t really gotten any easier to find a place to fill up. It may actually be harder.

More than once this year, we’ve found ourselves looking for a diesel station with the needle pegging Empty, only to pull up to a pump and find we can’t use it.

The problem is that there’s no longer one type of fuel that can fill up any diesel-powered vehicle; there are five different types, including ones for off-road equipment (bulldozers and such), heavy trucks, and cars. And even within the on-road diesel fuel, there are two types of nozzles, large ones for trucks and smaller ones for cars.

And that’s where we’ve run into problems, trying to fill up at stations with car pumps at islands designed for passenger cars. Once, driving our excellent Mercedes-Benz E250 Bluetec, we showed up at a station that had only one available diesel pump, only to find that it was equipped with a large truck nozzle that wouldn’t fit in the sedan’s filler neck. Another time, on a long trip to Boston in our BMW 328d, I was counting on filling up close to my destination, where I know fuel prices are lower. I was pleased to find a diesel pump at a little-used rest area right outside the city where we commonly stop, then dismayed to find the diesel pump tagged with an “out-of-order” sign. The only other diesel pump available where the attendant tried to send me was at the truck island, where I naturally found another large nozzle that wouldn’t fit our BMW.

For tips on saving gas—or diesel—visit our guide to fuel economy.

The difference started out a few years ago, when diesel cars were first required to use new cleaner diesel fuel, while large highway trucks were not yet. The smaller nozzles and filler necks for cars were designed to prevent them from filling up with unauthorized truck fuel. But now, on-road trucks and cars use the same type of fuel. Trucks still use larger nozzles, because they have bigger tanks and presumably want to fill them faster.

But at many stations the pumps with the different nozzles aren’t labeled, so you can’t tell before you pull up whether you can use them with a car. The attendant at the station where I tried to fill up our Mercedes said that oversized nozzle was a replacement for a smaller one that had broken. This is the third time I’ve experienced an incorrectly sized nozzle in the last year. And I’m not alone; several colleagues have likewise found truck nozzles at the car islands.

We think that if diesel pumps are going to have different nozzles, they should be labeled so car and truck drivers each know where to go to fill up. And if diesel cars are ever going to succeed, stations that sell the fuel on islands accessible to cars should be required to have at least one well-labeled pump with a nozzle that fits cars. That sounds like common sense to us.

—Eric Evarts

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