Cars & Trucks

Behind the wheel of vehicles of all types.

Are diesel benefits worth the fuel cost?








Categories: General
Tim Spell

20 Responses

  1. Markd says:

    Good question . . . without an easy answer. I am thinking about purchasing an SUV. We make many long highway trips so comfort during and at the end of the trip is as important as fuel cost. I compared the diesel cost to premium gas as opposed to regular since those were my real choices for the models I am considering purchasing. Diesel normally has been running about 50 cents a gallon more than premium.

    The Mercedes GL 320 CDI (turbo diesel) has 215 horsepower and 398 lb-ft torque. Surprisingly good acceleration from a stop but anemic trying to pass at highway speed. The EPA est. is 18 city and 24 highway. Compared to alternatives that get, say, 12 city and 18 highway you can save some significant gallons. Even better, Automobile Magazine (April 2008) found the MB GL 320CDI got real world performance of 23 city and 27 highway .

    Using the EPA estimates, based on assumptions fitting my use (ie. 1/3 city and 2/3 highway driving and at 50 cents per gallon over premium), the GL 320 diesel would save about $74 per month and 425 gallons per year.

    Not all gas stations carry diesel. Those that do carry it don’t all carry “premium” diesel that these engines require. I stopped at 5 gas stations that had diesel on their sign . . . only 2 had Ultra Low Sulfur Diesel as opposed to low sulfur. This makes me concerned about out of town trips and finding fuels when you need it. I did not check the truck stops yet.

    According to Car & Driver Magazine (April 2008) about 1/2 of new car and truck sales in Europe are diesels. Gasoline there is about $7.50 per gallon and diesel is about $1.00 cheaper. Further it says that most U.S refineries make about 50% gasoline and 25% diesel from a barrel of oil. 1 of every 8 gallons of gasoline that we consume in American comes from Europe. “Meanwhile, Americans are already using most of the diesel fuel that our refineries produce, so if sales take off, keeping diesel fuel flowing here will put further demands on tight world wide supplies and cause the price to rise even more”.

    I don’t expect the trucking industry to decline in shipping goods to market across the U.S., so expect the price difference from gas to reduce, probably significantly.

    However, even if the cost is not a primary factor to switch to diesel, would the gallons saved be enough to reduce America’s dependance on foreign countries for our energy needs. We would reduce the purchase of imported gasoline but will likely be importing diesel fuel to offset much of that. In my situation, assuming 25,000 miles per year, I would save about 425 gallons of fuel per year or 35 gallons per month. If that saving in fuel gallons translated into insignificant cost savings would I still want a diesel? Probably not.

  2. Ken P says:

    We have a 2000 VW Jetta TDI (diesel). The average mileage for the 160,000 miles we’ve driven the Jetta is approximately 44 mpg, with a high of 51 mpg on an all highway cross country trip.

    When it comes time to replace our Jetta, we’ll very seriously look at replacing it with another diesel. Currently the price differential is about 16% between diesel and regular, and we’re achieving about 40% better mileage with the diesel when compared to a similar gas powered Jetta.

    Regarding being able to find diesel fuel, here in Houston it’s not a problem. Within a 5 mile radius of Seabrook there is three Valero’s, one Exxon/Mobil, one Murphy (Walmart), one Conoco, and one Chevron. And I may be missing a couple. All stations are required to carry ULSD diesel at this time.

  3. lil ol me says:

    do the math. If the higher cost is offset by the higher mileage, go for it.

    At the moment, and rounding a bit, diesel is running about 15% more than gasoline per gallon.

    So…if the diesel vehicle gets 15% or better mileage than the gasoline version, it’s a deal.

    If not, it’s not.

  4. lil ol me says:

    Markd wrote:


    Ah, the old supply-demand law. You are exactly correct: as the demand for diesel increases and the demand for gasoline decreases, expect the difference between them to decrease or even flip.

  5. Charles Hixon says:

    Diesel power does not currently meet my needs. As far as giving them a shot in the future, I’m not in a hurry and will let the market decide.

  6. markd says:

    I wrote “… so expect the price difference from gas to reduce, probably significantly.” Actually, I wrote that totally the opposite of what I meant to write. I should have said “increase over gas”. What I was thinking is we are consuming almost all of the diesel that we are able to manufacture in the U.S. Trucking industry will continue to grow and with more diesel cars and SUV’s coming out there should be even mored diesel demand. Where will it come from? If we start importing diesel, it would seem to follow that the price would go up. Just guessing but I am I not sure that the price of gasoline would change.

  7. Tim Spell says:

    Here’s a view on that from the story featured in Sunday’s Cars & Trucks:

    “The American Petroleum Institute attributes the fast-climbing price of diesel to several factors. Diesel is a close relative of home heating oil, so costs have conventionally risen in the winter. And while demand for regular gasoline is slipping, diesel use actually has climbed and production is at capacity.

    Refiners spent $8 billion in past years to reconfigure their plants to produce cleaner, reduced-sulfur diesel. According to the U.S. Department of Energy, refining costs make up 21 percent of the cost of diesel, whereas refining costs for regular gasoline are only 8 percent of the total cost. Refiners are looking to get their investment back.

    When gas prices go up consumers can use less, but if diesel fuel goes up, trucks, which right now are the big users of diesel, still have to keep on trucking. Diesel use doesn’t fall, so demand is not susceptible to price fluctuation as it is with gasoline.”

  8. David in Chester says:

    My pickup uses diesel. To start with I paid $6,000 more for that engine and when I did diesel fuel was cheaper than regular gas but now is quite a bit more than premium gasoline. I’m being killed right now on this.

  9. lil ol me says:

    That’s ok, David, if you get a 33% increase in mileage with your diesel, you’ll break even in 10 years……

  10. craig says:

    If a person drove lots of miles a year a diesel might make sense. I don’t and am thinking about either a much more fuel efficient gas powered model or possibly a hybrid for my next purchase. No matter how clean and quiet they make them I still can’t shake the memory of diesels as being smelly and noisy.

  11. Larry Kolb says:

    Diesel fuel weighs about 20 percent more than gasoline. If we bought fuel by weight rather than volume, about half of the diesel fuel economy advantage disappears.

  12. James says:

    I am waiting now to buy my next car but I will continue waiting until the car companies offer European style diesels. When I drive in Europe I rent turbo diesels which are much more efficient and perform much better than petrol models. If these companies would only offer drivers in the US what they offer overseas we would all save.

  13. Lewii33 says:

    I drive a diesel suv, a Jeep Liberty 4×4. I get a steady 22 mpg, while the gas version Liberty 4×4 gets around 14 mpg. I drive between 100 and 150 miles per day, and my job requires me to have a 4 wheel drive. There is nothing out there that comes close to being as economical as this vehicle, even with the cost of fuel. Too bad they quit making them. I don’t know what I’ll do when I wear this one out in the hopefully way distant future.

  14. VW Driver 4-ever says:

    I am on my second VW Golf TDI and I average 45-50 mpg. I would buy another one in a heartbeat. Folks can make Diesel fuel from waste products. I can’t make gasoline. I will wait for the change. Granted I drive as little as possible these days, I am on a very tight budget.

  15. Ryan says:

    I remember not to long ago that Diesel used to be cheaper than gas. What happend?

  16. JRL62 says:

    I own a 2005 Mercedes E320 CDI with about 55,000 miles. The car was EPA rated at 27 city/37 highway. My city driving generally averages about 24 mpg. I range between 35-38 mpg on the highway. I am very pleased with the performance and economy of the diesel engine. It has significantly more usable torque than the gasoline motor. Although diesel costs more per gallon, the extra price is more than offset by the increased mileage, especially if you consider that a gasoline powered Mercedes calls for premium unleaded. I figure as long as the spread between gasoline and diesel remains less than $1.50 per gallon, I come out ahead. The diesel version of the Mercedes is only $1,000 more than the 6 cylinder gasoline model, and about $5,000 less than the V-8 model, so it is a good buy. Plus, the resale on my diesel model is about 6 or 7 thousand more than the 6 cylinder gas version of the same car. The modern high-preesure diesel engines sold in Europe are not anything like what Americans saw 20 years ago. If/when they become widely available here, they will probably become a popular alternative to hybrids. If Ford or GM could ever develop a deisel engine for their half ton trucks and passenger vehicles that didn’t cost an extra $7,000, people would buy them. Until then, they will watch their sales continue to decline.

  17. Grungy says:

    My 2005 Jetta Wagon TDI with manual transmission gets 45mpg without the AC and about 42mpg in the summer with the AC blowing. A tank of fuel is good for about 600 miles in the winter, and about 550 – 575 in the summer. Another thing to compare is tune-up costs – or the lack of them. I’m not sure how often most modern gasoline engines need a tune-up, but it has to be more often than my diesel. I really like not having to worry about spark plugs, wires, distributor cap, rotor, and timing. It’s not just dollars and cents. My previous daily driver was a VW Vanagon which got 18mpg day in and day out – about 225 miles per tank. I lived at the gas station back then – having to fill up just about every-other day. The long range really paid off when we were caught in the traffic fleeing Rita. After 16 hours on the road to go 180 miles, I still had half a tank. My daughter’s Golf TDI was blasted out from under her by someone running a red light and we are struggling to find a replacement with similar MPG characteristics. I’ve been disappointed by poor fuel efficiency of nearly all of the non-hybrid gasoline vehicles, and VW won’t have new TDIs in the stable until October. I’m not going to buy anything that gets less than 30mpg (city).

  18. John says:

    There is a couple other things good about a diesel engine. And these couple other things is why I plan to buy one. Biofuel… the diesel engine, as far as I know is the only engine that needs no modification to run on biofuel. I’m speaking of course of biodiesel. I’ve learned that biodiesel is even made in the comfort of one’s own home. Sure I can buy it at the pump, but I think I may stand to save a tremendous amount of money just by researching and learning to do it in my own garage… well as soon as I get my own garage that is. And if I can make that vehicle last, it doesn’t matter what happens to fuel prices, there will always be enough resturants around to obtain vegetable oil that I can filter out and convert to biodiesel. Not to mention if I get tired of doing the homemade biodiesel thing, I can just buy the conversion kit to allow my vehicle to run on regular vegetable oil. I really think biodiesel is going to become a lot cheaper in time because I also recently learned from a friend of mine that did a research paper on biofuel for his class that biodiesel can be manufactured from a common bacteria that grows inside of water storage structures such as a water tower. If this is true, then we don’t even have to use food supplies to provide this fuel source, but we still could use excess oils from resturants that would be thrown away anyhow. If I ever owned such a business that’s what I’d do, I’d start buying up excess food and oil at a cheap price that is scheduled to just be thrown out, and I’d have acres of bacterial growth chambers to manufacture enough biodiesel to provide for the demand of fuel. As a matter of fact, my friend and I have actually discussed it once as a passing thought, but I’m giving it some concideration now as I’m writing this actually. My friend happens to be have bachelors in chemistry, and is working towards his Doctorate at UTEP. With his knowledge, we could start out small, but we might actually be able to do it in time. I think I will go meet him and tell him that I think we should at least find out how we could get started if we decide to take this route. Thank you.

  19. rusty47ford says:

    I bought a diesel Grand Cherokee Overland in January. It gets the same fuel economy as a six cylinder Ford Escape or a Suzuki Grand Vitera. One thing that I discovered post purchase – the Daimler diesel in it has gears – not belts – to drive the overhead camshafts – big savings over the life of the vehicle!

  20. Eyelid says:

    FYI, most uk diesels have a big red warning sticker saying ‘NO BIODIESEL’ inside the petrol cap. Im sure that anyone who DID use it, would void their warranty. Nice point about offsetting it by calculating mileage, got to do some sums now dammit !!