Diesel Dilemma

By Eric Peters, Automotive Columnist

Summer’s coming — and so (probably) are higher gas prices. There has already been a nationwide uptick of about 40 cents a gallon over the past few months — and we’re still a few weeks away from spring. It’s likely we’ll see over $4 a gallon gas after spring arrives — and maybe more than that by high summer. (In California, gas is already close to $5 a gallon.)

Even “cheap” $3 a gallon gas is about twice as expensive as it was just a few years ago. We’ve just become used to it. But that doesn’t mean we can afford it.

Diesel-powered cars could be our salvation — and a bunch of new ones are going to be available within the next 6-12 months, including diesel versions of the 2014 Jeep Grand Cherokee SUV and Chevy Cruze and Mazda3 compact sedan/hatchback wagons. These will go much farther on a gallon of fuel than their gas-engined equivalents. The diesel Cruze and Mazda3, in particular, should be capable of averaging close to 40 MPG — and (unlike most hybrids) remain exceptionally fuel-efficient at highway speeds.

But, there’s a fly in the soup. Three flies, actually.

First, there’s the higher initial cost of a diesel-engined car vs. its gas engined-equivalent. The MSRPs of the ’14 diesel Grand Cherokee, Cruze and Mazda3 haven’t been revealed yet, but in the past — and right now — a diesel typically costs about $2,500 more “up front” than the same car with a gas engine. Sometimes, considerably more than that. As an example, a 2013 VW New Beetle diesel lists for $23,295. The standard New Beetle (with gas engine) stickers for $19,795. While the diesel Beetle is much more economical to operate (28 city, 41 highway vs. 22 city, 31 highway) it’ll take at least a few years of driving to work off the diesel’s $3,500 price premium. And that’s assuming you’re in a position to do so. For many buyers, ponying up an extra $3,500 at buy-time (or finance time) just isn’t doable — even if the car costs less to operate.

Second, there’s the fuel issue. Though a gallon of diesel will take you farther down the road than a gallon of gas (especially a gallon of ethanol-adulterated “gas”) it also costs more to buy the gallon of diesel — chiefly because of government “ultra low sulfur” diesel fuel requirements. Diesel used to be cheaper to buy than gas, in part because diesel used to cost less to refine. Now, it costs more — because of the ULS requirements, which have increased refining costs significantly. These costs — imposed by the government — are passed on to consumers.

At the time this article was written in early March 2013, diesel was selling for just a few cents shy of $4 a gallon in the Southeast — about 30-40 cents more per gallon than regular unleaded. That’s no small thing when factored out over a period of years. It could in fact be a large enough thing — if that 30-40 cent per gallon spread stays roughly constant during the years you own the vehicle — that (combined with the higher up-front costs you had to pay) you end up about the same (money wise) as you would have had you bought the gas-engined version of the vehicle.

Which brings me to the third issue — which is related to the second issue (ULS diesel fuel). To comply with ultra-strict tailpipe emissions requirements (specifically, oxides of nitrogen) many new diesel-powered cars have some form of urea injection. The urea is not burned in the engine but sprayed into the exhaust stream to chemically alter the exhaust before it leaves the tailpipe. It is akin to catalytic converters in gas-engined cars, but with a difference: The urea tank must be periodically replenished. And the urea isn’t free.

So, how much does it cost?

Here’s one example: The urea tank in a current (2013) Mercedes M-Class diesel holds about 8 gallons of “AdBlue” urea. This is sufficient — according to Mercedes — for about 10,000 miles of driving. The urea costs (at current prices) about $16 a gallon.* So, it costs about $130 extra every 10,000 miles to operate the vehicle. Over 100,000 miles, that’s an additional $1,300 in operating expenses.

It’s not a huge expense — in isolation. But when you add that expense to the expense of the diesel vehicle itself (a new Benz ML350 diesel stickers for $51,270 vs. $49, 770 for the gas-engined equivalent version) then factor in the higher cost of the diesel fuel, diesel loses a lot of its economic luster.

However, there are a few important things that must also be said in defense of diesels — things that can greatly compensate for the issues raised above.

First, diesels last. Because they (usually) have extremely high-compression ratios (to ignite the fuel by pressure and heat rather than spark, as in a gas engine) they are (again, usually) built much stronger — tougher blocks, tougher internals. Built right, treated right, a diesel engine should be capable of at least 200k — without more than routine service. That’s how you can make your money back — especially relative to a hybrid car. While hybrids have proved to be very reliable and durable, their gas engines — and electric batteries — aren’t made to go a quarter-of-a-million miles. Diesel engines — historically — have gone that far routinely. But remember: To make the math work for you, you’re probably going to have to put a lot of miles on the clock.

Second, diesels — modern diesels — perform. As in — they accelerate. Quickly. Unlike most hybrids. Which don’t. A modern diesel-powered car is fun to drive.

Few hybrids are.

And, lastly, in the event things really go sour — as in a SHTF-type of scenario — it will be much more feasible to keep a diesel-powered vehicle going, because (leaving aside the issue of emissions) you’ll be able to use home-brewable biodiesel, even perhaps waste vegetable oil. Gas, on the other hand, is a much more refined fuel that requires the facilities of a refinery.

* The cost quoted of adding urea assumes you buy — and add — the urea yourself. If you pay the dealer to do it, the cost can be much higher. Consumer Reports had a dealership refill a Benz G-Class diesel and were presented with a bill for $317 for 7.5 gallons of Adblue.



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2 Responses to “Diesel Dilemma”

  1. meetooo says:

    The problem with comparing diesel to gas consumption wise is the current epa rating is admitted to, documented by the epa in testing paper work to be in error low by at least 21 % on all light duty diesel ratings.

    If you compare the real numbers, real world numbers the manual trans diesels should add another ~20 % above current epa rating when comparing. Any of the manual trans equipped 2.0L TDI-CRs easily return mid to high 40s mpgUS in mixed driving. City driving they return high 30s to mid 40s city. And on highway only loops they can easily exceed the 50 mpgUS mark.

    Today the most efficient of the models equipped with the 2.0L are the manual trans Passat TDI-CRs with urea. Real world city high 30s to low 40s city, low to high 40s mixed loops, high 40s to low 50s mpgUS highway.

    The current Jetta, Golf, Golf wagon, NB and Audi A3 TDI-CR with the auto shifted manual automatic "DSG" real world numbers are the admitted to by the epa of 21 % low in their testing procedure data. Real consumption numbers on these diesel powered models are mid to high 30s are normal city, high 30s to low 40s mixed and mid to high 40s to ~50 mpgUS highway.

    You want real numbers on any of the currently offered in the US today to compare for the article's purposes use the Resources Canada or EU test figures. Those are in line with what is reported regularly on the TDIclub fuel consumption related threads.

  2. SherDan says:

    The higher costs you mention are much less of an issue than you make them out to be. Diesels come out ahead of gas in every way.

    The initial higher cost of a diesel is usually recaptured when you sell the vehicle. Look at the used prices for TDI's vs. VR6 Touareg's for instance, and you'll see what I mean. Non-issue made even less relevant by the longevity of a diesel. Depreciation is the biggest cost for a vehicle, and it's generally far less with a Tdi.

    The cost of adblue/urea is a non-issue. Go into any truckstop and you can get the stuff for a lot less than you quote here. 2.5 gallons is usually less than $15, half of what you quote here from the dealers.

    Comparing diesel fuel cost against regular doesn't really make sense when most the gas equivalent for most of the cars that have diesel engines require premium anyway. Just about every German gasser requires premium, so the fuel cost difference is minimal. Even if you compare against regular, a 40 cent difference is 10% of $4.00, but the diesel gets around 30% better mileage per gallon. I'm not a math wiz, but that sounds like a bargain for the diesel to me. Gets much better if you correctly compare against premium.

    Plus there's the pure fun of driving a car with a torque curve that peaks at low revs. Turbo diesels are a blast to drive.