The latest hubbub has been all over the forums and automotive news sites about Toyota considering a Cummins diesel engine. While it has been fun watching the all the buzz, it is time for us to weigh in. I talked with Toyota’s national brand manager, here is the real deal.
Diesel engines are superior to gas engines in a few critical ways:
- Diesel engines are more efficient due to the thermodynamic benefits of their higher compression ratios
- They’re much more durable – diesel engines commonly run 2-3 times longer than a comparable gas engine
- They put out more torque for any given RPM than a similarly sized gas engine, meaning that a tiny little diesel engine can power a small car very efficiently (Ford’s euro-spec Fiesta diesel gets 60+ mpg with a 1.6L motor)
Point #1 and #3 are very important, as they are the main reasons that diesels are so popular around the world. In Europe, for example, about 50% of the vehicles (be they tiny little commuter cars or big trucks) are powered by diesel. Considering that the average cost of fuel in most Western European countries ranges between $6-8 per gallon (1.27-1.72 euros per liter), the fuel economy benefits of diesel engines make them a very popular option.
Yet in the United States, diesel vehicles are barely 5% of the market. Why? What is it about diesels that people in the USA dislike?
The answer? Emissions rules, the “carbon penalty,” and a myriad of other smaller issues keeps diesels from selling. What follows is an attempt to explain – comprehensively – why diesels don’t (and probably won’t ever) sell at any substantial volumes in the USA.
Sometimes some of the most innovative design ideas rely on concepts that are actually very, very old. History is littered with theories, materials and feats of engineering that were patented long before their time, intriguing developments that simply were not capitalized on in their era for a variety of different reasons. One technology that falls under this general heading is compacted graphite iron.
Compacted graphite iron (CGI) was developed more than 60 years ago as a high strength alternative to standard gray iron. In fact, CGI is 75 percent stronger and stiffer than traditional gray iron, and it also offers better resistance to fatigue than both aluminum and gray iron. This strong and lightweight material was used only sparingly over the decades following its discovery, with applications including high speed train brakes and commercial diesel truck engines.
In a more modern setting, CGI has found its way into the factories that produce premium luxury cars, such as those run by BMW and Audi who use the metal in a number of different engine designs. Jaguar and Hyundai have also adopted the use of CGI in several high performance applications. In the motorsports world, NASCAR has heavily adopted CGI technology, with the majority of teams using this material for their engine blocks which see some of the harshest abuse that a motor can take. Even TRD has gotten into the act, using a CGI block for its Craftsman series racing truck engine.
For half-ton truck owners, the most intriguing possibilities offered by compacted graphite iron relate to its potential in the lightweight diesel field.
In what we hope will not be the last post we ever write about the subject, we’ve taken some time to create a page dedicated to the story of the diesel Tundra.
As you may or may not know, Toyota has flirted with the notion of building a diesel version of the Toyota Tundra for some time. Originally, Toyota’s plan was to attack the truck market with both a big powerful HD diesel Tundra AND a powerful yet fuel-efficient diesel version of the half-ton Tundra. Sadly, slow sales and a slow economy have halted these plans.
In what may be considered good news, we have it on high authority that Toyota has done more than just design a half-ton diesel – rumors of an actual working half-ton diesel Tundra seem to be legitimate (yet we have no photos).
For as long as I can remember, truck enthusiasts have been clamoring for a half-ton diesel. Diesel engines offer a lot of advantages over gasoline motors, many of which truck owners find particularly appealing.
Diesel truck advantages:
- Diesel is more efficient. Depending on who you ask, diesel engines are about 30% more fuel efficient than a gasoline engine of comparable size.
- Diesel engines are heavy on torque. Diesel engines provide gobs of torque at very low RPMs – much more than a typical gas motor.
- Diesel engines run a very long time. Your typical diesel truck engine will run 200k miles minimum before a problem develops. For gasoline engines, 120k miles is a more realistic “no problems” life span.
Of course, it’s not all roses and horsepower with diesels – here’s a few reasons diesels aren’t better than gasoline: