I've had a number of diesel-powered daily drivers in the past few years that led to countless conversations debating the value of oil-burning engines. The dollars and cents is only one variable in a much bigger equation. A full tank of diesel carries a price premium roughly equal to a Double-Double Combo, but skipping a cheeseburger with every trip to the pump gets you a mountain of low-end torque and cruising range that will surely beat your bladder's. The diesel-based 2015 BMW 535d is the best all-around version whether it saves you money or not.
In 2014, both gas and diesel were substantially more expensive than they are now; I normally paid a decent margin over four dollars for a gallon of diesel. At my normal stations, a gallon of premium gasoline was usually within 5 percent, plus or minus depending on the week. Most people, however, swore that diesel was far more expensive, maybe as much as 40 cents a gallon, which as you math-minded readers realize is around 10 percent. Telling people that diesels are as much as 30 percent more efficient is futile when all they see is an extra outlay at every fill-up.
As I write this, diesel fuel has fallen significantly in price—but not as much as gasoline. Currently, the Chevron down the street is getting $2.78 per gallon of premium, while diesel is still $3.09 per gallon. The EPA rates the gas-powered 535i at 31 highway mpg and the 535d at 38 mpg. So every mile in the gas 535i is roughly nine cents, while the diesel is roughly eight cents per mile. Which means, in just 150,000 quick miles the diesel will repay you the $1,500 premium you paid. In fairness, I should also point out that historically at least, diesels have demonstrated noticeably better resale value that often surpass the new purchase price difference. A quick web search shows 535ds are shifting hands at roughly two grand higher than its gas-powered equivalents.
So, yes, even with cheaper gas it still makes sense to buy the diesel, but as I've stated earlier, that isn't the best reason to buy a diesel. The 413 lb-ft of torque generated by the turbocharged 3.0L is. The diesel is 45 hp down on its gas counterpart at only 255 hp, which is rated at 300 hp and 300 lb-ft of torque. For most driving, the extra 113 lb-ft of torque is far more useful.
At our test track, both cars ran an identical 5.5 seconds from 0-60 mph. The gas-powered 535i edged out the 535d in the quarter-mile running a 14-second flat compared to the 14.2 seconds. Trap speed was to the gasser also at 99.3 compared to 97.1 mph. In normal driving, however, the diesel feels far more responsive and requires fewer shifts from the eight-speed automatic. Obviously, neither car has the old naturally aspirated feel old-school Bimmer fans once knew. For the most part, I'm OK with that. With each generation, the 5-series has added more luxury to the sports sedan equation.
The ride is firm, but controlled. This particular car was equipped more toward the sporting end of the spectrum and feels appropriate. The car absorbs but doesn't mask what the car is rolling over. You will know when the road is rough; you will know the suspension is working to attenuate the big bumps. They won't upset the car and they certainly won't upset the occupants' beverages. How does that translate to handling? Quite well actually.
On the road, the 535d's confident athleticism is a bit at odds with its ever-expanding girth. It's a big car, but it can move. The large backseat invites passengers who may not appreciate the gusto this car encourages on freeway ramps and backroads. My son, however, loved it. There is certainly body movement, but it doesn't detract from the experience. It actually may encourage it some, as all 4,085 pounds of mass can be shifted around with the throttle.
At the track, the car becomes more fun, and exploring the car at its limits illustrates the extra effort BMW engineers put into the chassis. DSC Sport mode allows for a pretty fair amount of on-throttle rotation before it steps in. With all the electronics defeated, the big 5er will swing its tail around with ease. This isn't a subtle car; it doesn't like soft inputs. It prefers a bit heavier hand and likes to be pushed around a little bit. Slow, easy inputs result in gentle understeer, and you can put all the power down with a widening arc. Turn in a bit more abruptly and jab at the gas pedal and you get far more response. It's easy to overdo it and break the front tires loose, or even get the car too sideways and scrub all your momentum. Get it right and you get a satisfying and quick sideways drift on exit.
The advantage of the diesel's midrange torque is illustrated on the figure-8. While the 535i was a little faster in the quarter-mile, and consequently faster toward the ends of the straights, the 535d can get off the corners faster. The 535d turned in a 25.8-second lap, which is a tenth faster than the 535i. It is worth noting that the 535i was able to out-stop the 535d by a notable margin, 106 feet compared to 112. The diesel version is a mere 78 pounds heavier, which is negligible.
Besides the track and enthusiastic road driving, I did get a chance to use the 535d on a road trip as well. My average speed was likely higher than what the EPA considers normal. Over the roughly 600-mile trip, the BMW averaged 36 mpg. That includes some traffic and in-town driving as well. Observed fuel economy is by definition anecdotal, but it gives you an idea of what the car is capable of.
Our tester came in at $66,425 and felt lightly equipped. It didn't even have a rearview camera, much less around view. The car itself still feels well built and solid. Everything in the car has a heft and firmness. Nothing flexes or bends under load. The seats, once adjusted, feel as though they are welded in position. There is no movement in the backrest, no creaking, just support. The controls all feel modern, with a rubbery detent in buttons and knobs.
The steering wheel is a long evolution of BMW design. It isn't overly thick, like some previous cars, and won't tire hands by being too soft. All in all, the car is a pleasure to be in for the long periods of time afforded by roughly 700 miles of cruising range.
If I were buying a 5-series tomorrow, the diesel would be a no-brainer. Even if it returned the same fuel economy as the gas version, the torque and resale value would make the decision for me. Those things coupled with the extra fuel economy are a bonus.
Diesels are still a bit of a niche product in North America, but the European fans are without a doubt the most deeply involved. The 535d is a prime example why.