Three Hundred Miles Without Thinking About It: Why the Yukon Duramax Makes Sense

The 3.0L Duramax turbo-diesel inline-six produces 305 horsepower and 495 lb-ft of torque. It carries an EPA-estimated 21 mpg city and 26 mpg highway in rear-wheel drive (20 city and 24 highway in four-wheel drive) and can be ordered on every trim from Elevation to Denali Ultimate.

The distance from Torrington to Boston and then back is a little short of 300 miles; if you make that journey in a full-size SUV with the family on board you will have noticed a number of things by the time you pull into the driveway.

You think about fuel more than once; you check whether passing a truck on the Mass Pike required some planning and you observe how loud the cabin became at 70.

What the engine actually is

The Duramax engine in the Yukon is constructed in such a way that you cease to notice it; it is a 3.0-liter turbocharged inline-six diesel coupled with the same 10-speed automatic transmission as found on the gas engines and produces 305 horsepower and 495 lb-ft of torque.

Place it alongside the other two options. The standard 5.3L V8 produces 355 horsepower and 383 lb-ft, while the available 6.2L V8 produces 420 horsepower and 460 lb-ft, and General Motors advises the use of premium fuel with it.

The diesel engine gives up horsepower to both units. Although it appears to be the weakest of the three when looked at on paper, in reality it doesn't work that way, and the explanation lies in where the torque is.

The Duramax produces its torque within the rev range that you actually use, with a peak torque of 495 lb-ft coming on at 2,750 rpm and peak horsepower appearing at 3,750 rpm. The entire usable rev range is low.

When considering merging onto the I-84, going up the slope outside Waterbury with seven people and a roof box, or getting a heavily loaded trailer moving from a complete stop, the torque that you can obtain without winding the engine out is greater than the torque produced by a V8 engine which develops its maximum power near the top of the rev counter.

The inline-six arrangement also helps since the six cylinders arranged in a row balance each other and thus result in less vibration during a long journey.

The fuel numbers, stated honestly

The EPA gives the Yukon Duramax ratings of 21 in the city, 26 on the highway and 23 combined when it is in rear-wheel drive; when it is in four-wheel drive the ratings are 20 in the city, 24 on the highway and 22 combined.

In some places 27 mpg highway will be quoted; that figure is based on real-world testing rather than the EPA rating, so use 26 as the figure.

The majority of buyers in this area should be considering four-wheel drive, and it isn't provided in the same manner on all the trim levels. On the AT4, the AT4 Ultimate and the Denali Ultimate, four-wheel drive is standard fitment, while on the Elevation and Denali models it is available, the latter two coming with rear-wheel drive as standard. Therefore the 26 mpg figure on the highway applies to an Elevation or Denali with rear-wheel drive, and that setup is difficult to justify in a state that has such severe winters.

Although the combined figure is only 22, the difference compared to the gas engines is still there. Both of the V8 engines come in at about 16 to 17 combined, depending on the drivetrain and the source. The diesel is considerably more efficient regardless of which version you choose.

Available on every trim, which is unusual

A really good point about the pitch is that the Duramax engine is available on all five trims: the Elevation, the AT4, the AT4 Ultimate, the Denali, and the Denali Ultimate.

Engine lineups are generally not arranged like that. For example, the 6.2L V8 is not available on the Elevation model at all, and in many cases the more interesting engine is reserved for the more expensive trims, which means you end up having to pay for leather that you didn't want just to get the powertrain you wanted.

Not here; the diesel engine is offered in the entry-level Elevation or in the six-figure Denali Ultimate. Regardless of your budget, the engine is one of the options.

Before you go shopping, you should clarify one point: there is a disagreement among sources regarding which engine is fitted as standard on the two Ultimate trims. While some state that it is the 6.2L V8, others say that it is the Duramax with the V8 then being an optional engine. So ask the dealer to verify the exact vehicle rather than relying on a specification sheet.

Now the part nobody wants to write

There is a cost associated with the Duramax, and the nature of that cost will vary depending on the trim you have chosen. When a gas V8 is standard on a particular trim, the diesel engine then represents an extra charge; however, on the Ultimate trims, as mentioned above, it might not be an extra charge at all. 

You should ask about the figure for the specific build you are considering, since the amount given in a specification sheet will not be the same as the one that appears on your window sticker.

When you have it, carry out the calculation before deciding whether it breaks even.

Begin with gallons. A rear-drive diesel engine, using 23 combined miles per gallon, consumes approximately 652 gallons when driven 15,000 miles a year, while a rear-drive 5.3L engine, achieving 17 combined miles per gallon, uses about 882 gallons; the difference is 230 gallons per year.

The gap narrows but does not close with four-wheel drive, the diesel achieving 22 combined miles per gallon using approximately 682 gallons compared to the 882 gallons used by the 5.3L, a difference of 200 gallons.

Calculate the actual cost of fuel when you go to the pump. In Connecticut diesel tends to be more expensive per gallon than regular gasoline, so your savings are not just equal to 230 gallons multiplied by the pump price. You should work out how much you would pay for each type of fuel over the course of a year, find the difference between these amounts, and then divide the diesel option price by that difference.

For a person who drives ordinary distances, the reply takes years rather than months to come. If you drive 25,000 miles each year, the situation becomes much more favorable. But if your annual mileage is 8,000 miles, you'll have to trade in the vehicle before you recover your money.

You should choose the Duramax because of the way it drives and the way it handles towing, and consider the fuel savings as an extra benefit; anyone who is selling it to you on the basis of it saving you money has not done the relevant calculations.

There are two further ownership considerations: the diesel engine requires DEF, which you have to replenish from time to time. Although it's easy to locate, it does add one more item to keep in mind. Moreover, not all gas stations offer a diesel pump, so your filling-up procedure has to be a bit altered.

The towing footnote

It's a surprise to many. The 5.3L gas V8 with rear-wheel drive and the Max Trailering Package has the Yukon's top tow rating of 8,400 pounds, rather than the diesel engine. In the same rear-wheel-drive configuration the Duramax reaches about 8,100 pounds.

However, consider four-wheel drive, since that is what most people here will actually order. The Duramax has the highest rating of the three, around 7,900 pounds, beating the 5.3L which is 7,700 and the 6.2L at 7,500 when the Max Trailering Package is not included; but when the Max Trailering Package is added, the 5.3L takes the lead at about 8,200 while the diesel remains at 7,900.

The diesel engine isn't the one with the highest figure on the specification sheet, nor is it the weakest in comparison, and the difference between these engines is only a few hundred pounds instead of being in different categories. For a person who regularly tows, the low-end torque and the improved economy when under load are more important from day to day than those final two hundred pounds of rating.

If you plan on having your trailer near the limit, work out the specific figure for your particular configuration before placing your order.

Who should buy it

The Duramax is suitable for a particular type of driver.

You achieve a high annual mileage, mostly on the highway, which causes the efficiency gap to increase.

You often tow, particularly when towing a boat or a mid-weight camper.

On long family trips, fewer fuel stops and a quieter cabin are advantageous.

You might just prefer the way a torquey diesel performs. That's a valid reason and doesn't need a spreadsheet.

It makes less sense when your driving consists of short trips around the suburbs, since diesel emissions equipment functions most effectively once it has reached its operating temperature and a car which mostly drives five-mile errands never does.

Where to drive one

The Northwest Hills GMC on East Main Street in Torrington carries the Yukon; you should call in advance and find out if they have a diesel on the lot or if they can arrange for you to drive one, since you'll want to drive the engine rather than just read about it.

Test it on an actual route by accelerating it up to highway speed, driving up a slope, and then noting how the engine performs when you request speed at 45 rather than from a complete stop. It is precisely in this situation that the engine makes its case.

When you're visiting the dealership, put two questions to them: one about the extra cost of the diesel engine on the trim you've chosen and the other about the tow rating of that particular model.

Three hundred miles is nothing to this engine. Just decide whether you want it for the drive or for the savings, because those are two different purchases.