Toyota's Direct Injection Four-Stroke Superior version (D-S4) engine combines direct injection (which injects fuel into the combustion chamber) with port injection (which injects fuel into the intake ports). It controls the two types of injectors in accordance with driving conditions. Under heavy load, direct injection is employed. Under medium or high load, both types are used. In the drawing on the left, the engine uses both types of injectors (port injection is marked as "1" at the top). On the right, the engine uses direct injection only. (Source: Toyota)
Wow, Chuck. I am duly impressed. I didn't realize there was such a wide swath of technology and innovations underway to address the 54.5 CAFE standard mandate. As you well noted, the focus tends to be on powertrain technology, yet there are many other places, many probably not considered, where auto OEMs can squeeze more mileage out of their designs. I particularly was impressed by the so-called "little things"--the improvements to making the wiring systems lighter and the flaps on the Chevy Cruze for aerodynamics. Very, very interesting stuff.
I agree, Beth. There are a lot of little technologies that eke out a few tenths of an MPG. The technology that will have the biggest impact, and will be most widespread, I think, is start-stop. Over the next ten years, we'll be seeing that on huge numbers of vehicles.
Beth, I too am exited that these technologies are being explored and implemented. I am not surprised, because many of these innovations are not new, certainly start-stop technology is something that is not new and could have been implemented 20-30 years ago (has been on the Prius for 15 years). My hat is off to DN and Captain Hybrid for bringing some of the new technologies to light, we have heard too many excuses as to why we can't reach CAFE standards, and not enough examination of technology and innovation. These are only 19 ways (there are many more existing) that can be used to increase mpg ratings, not to mention ideas that have not even been thought of yet. Interesting that none of these ideas force cars to be smaller, and they don't even include hybrid technology. Coupled with hybrid/electric technology, the 54mpg standard should be met easily if we stop fighting about it and start engineering.
The 600 ib gorilla is reliability. If most of these technologies ever fail in the field, the cost to repair will exceed the fuel saved. The energy required to make the repair parts might even exceed the fuel saved, a total false economy.
One in particular I would avoid like the plage is the aluminum wiring. It will be a disaster. Aluminum is NOT suited for wire.
Manufactureres must remeber the cost of poor reliability is loss of market share, always.
The real gorilla in the room is the driver. I don't know what kind of efficiency improvement optimal acceleration and decelaration would garner, but I bet it's significant. I'm always amazed at how many people gun it at the green light only to hit the brakes 500 meters farther down at the next light.
As for the technologies presented in this article, it looks like the engineers are doing their part.
The real gorilla is simply size and weight. All these admirable technologies simply allow us to extract incremental improvements in efficiency but as long as we use heat engines we are stuck with fundamental physics and the Carnot cycle. The physics of physical size on aerodynamics is pretty much fixed for practical vehicles that people can use for real transportation. Weight is the other one. There will be compromises. Vehicles will have to get smaller and lighter. Cutting weight is where the money is. Vehicle manufacturers have done very impressive work on making engines more fuel efficient, reduced emissions, and have kept performance pretty reasonable. I remember the gutless wonders that came out the the late 70's, early 80's. Chevy Citation anyone? Celebrity with the iron duke 2.5L? K-car? Remember throttle body fuel injection? <<shudder>>. Some of these cars had 0-60 times measured in minutes.
Cars are going to become more focused in their marketing/deployments. For instance, if you do mostly highway driving or country roads with few to moderate stops, a hybrid car becomes a liability because of the extra weight and complexity. Hybrids and start-stops make good sense for city cars and lots of in-town driving but their advantages disappear on the open road. Light weight, good aerodynamics, and simple, fuel efficient engines will yield very good results when the driving is biased towards the open road. Parasitic drag is another area that will yield significant improvements. Power steering and water pumps are prime for electrical replacements.
With all the customer and market interest in fuel efficient vehicles, why does the government feel it needs to drive this market? I can understand to some degree safety and emissions mandates as those are less tangible to the average consumer. But mileage? That's on virtually every one's mind.
If this country is serious about improving fuel economy then we need to invest in things like traffic circles and timing for stop lights. It's no secret that city fuel economy is nominally 30% less than highway economy. btwolfe mentions start/stop habits ... the best solution is to avoid the stop altogether since it takes far less fuel to maintain velocity than to accelerate to the same velocity from a stop.
Finally! Someone else sees this as a big picture issue. Traffic patterns in this country have severly degraded over the last 30 years (since the big recession in the '70s). Traffic lights have reverted from sensor oriented back to timed lights, and they are no longer timed together. Traffic circles, or round-abouts are non-existant. Stop and go traffic is a problem the government needs to resolve. Not tearing apart working, flowing interstate exits and replacing them with traffic light ramps that stop traffic as they are currently doing in my community. We seem to be going backwards in this area.
A recently released government report has raised the hopes of automakers looking for a break on future fuel economy regulations, despite the warnings of an Environmental Protection Agency official who said the agency is unlikely to back down on its goal of 54.5 mpg by 2025.
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