"Big rigs will have to slash fuel consumption by 23 percent".
 

Obama announces fuel standards for big vehicles - Yahoo! News

Who thinks that is do able?
I am not a semi truck operator or maintainer, is 23% more possible?
Those trucks get like 8 to 10 mpg and I am sure owner operators employ what ever tricks they can to improve that even if you only pick up .5mpg or 1mpg.

My guess is it would largely be aerodyanmic improvements.
When I moved from virginia to newmexico I hauled 6,000lb of stuff and towed my 3,600 lb car on a trailer. I got 8mpg, then had to drive the truck 50 miles to return it when empty. I still got 8mpg.

Heavy duty pickups having to get 10% better fuel economy is not challenge. That can be done easy, with out touching the engine its self such as with conversion to electric fans, different tires or gearing.
Fans alone or gearing alone would net +10% easy.

15% more fuel economy from a diesel pickup could be had with different tuning alone, no challenge what so ever.

Wow, those commenters, they're like straight out of South park.

In a decade their mileage will double.

regards
Mech

As someone who works as an engineer in diesel R&D, these types of governement mandates & regulations make me want to pull my hair out sometimes.

First off, the heavy-duty truck market (e.g., semi trucks) has pretty much always been the engine application that has natuarally put the highest emphasis on fuel economy. The free-market has naturally driven this. Heavy-duty truck buyers are willing to pay for fuel economy. It's simple to see why. If you do the math you can see that a 1% improvement in FE saves a truck owner almost $1,000/yr. Compare that to the average pickup owner who's hard-pressed to even notice a 10% improvement.

Very few people also know how much improvement has happened on it's own as well. I can't find the exact figures right now, but a while back I remember seeing a chart of average FE (in gal/ton-mile) of heavy-duty truck over the last 50 years or so. If I remember correctly, I think FE has nearly doubled since 1970. All this without regulation. Why? Because the market will pay for FE.

Trucks and engines can be made to get substantially higher FE today. But it's always a matter of cost. We can add additional technology to an engine (like more advanced fuel systems, more advanced turbos, etc.) that will improve FE, but if the increased cost is so much that it won't pay for itself, then the customer won't pay for it.

If you set a standard in a regulation one of two things will happen.

Here's the first scenario:
The standard is lower than what the industry would do on it's own. In this case, the standard was unnecessary, and cost the industry millions in extra money testing the trucks & engines to show the government that they met the standard.

Here's the second scenario:
The standard is higher than what the industry would do on it's own. In this case the government has forced to customer to pay for more FE than will pay for itself. For example, the customer will have to pay $15k more for a truck that gets 1% better FE (a 15+ year payback). Oh, and there's still the extra costs to the manufacturers for all the additional testing to prove they met the standards.

It just doesn't make sense to me.

I doubt a 23% reduction across the board is possible. Dump trucks,Cement mixers,log trucks and Heavy equipment haulers will always use more fuel. Bad aero, heavy loads and short hauls on secondary roads with lots of stops, just eats fuel.

Also, open flat bed trailers with their constantly changing load configurations.

>

This is a good move. However, I see the only way to meet the standards is using much smaller engines, that could be a problem for mountain regions and emergency trucks.

Yes it's possible, and without doing a thing to the engines. Consider the number of absolutely ridiculous aerodynamic designs available for sale *right now* - the Kenworth T-800 for example. Big, square hood, absolutely no curves to the entire vehicle other than the fenders. It's only aerodynamic features are a sloped hood and windshield.
Their T-660 (A so-called aerodynamic truck) is better - the hood is curved and sloped, the grille is as small as possible to still get airflow - but the sleeper is just like a parachute hanging from the back of the truck.

Then look at the Freightliner Coronado and Kenworth W-900 - these two relics should have been retired YEARS ago, although at least the Freightliner has some curves and aero features. There's absolutely no need to have a rolling brick like these on the highway, other than that people will buy them for their looks. I think the W-900 has possibly got the worst aerodynamics of any truck available right now. EXTERNAL air cleaners? Who does that anymore...
I just realized that both KW and Freightliner have snuck air fairings onto the back of these trucks - I'm assuming they figured none of their 'real truck' buyers would notice
http://i299.photobucket.com/albums/m...-1_640x480.jpg
http://i299.photobucket.com/albums/m...38fln/2900.jpg

Some examples of modern, aerodynamic trucks? The KW T-700 and Freightliner Cascadia (Everybody makes aerodynamic trucks, I'm trying to keep this post short)

Can't find a good picture of a T-700 quickly, here's a Cascadia - Notice all of the aero features missing from the Coronado and W-900 - Exhaust located behind the cab instead of stuck into the wind, air fairings over the fuel tanks ('skirts'), the hood is sloped and narrow towards the front and wide at the back to encourage airflow over and around the cab.
Also notice the top of the cab is curved instead of square like the W-900 to encourage the air to flow more easily over the top of the trailer the tractor is pulling
http://i299.photobucket.com/albums/m...er_800x600.jpg

The aerodynamic differences of these trucks can easily see a difference in fuel economy of at least 20% if not more. We've actually seen some significant differences on truck makes here - sometimes as much as 25% from one design to another.

Also, the fuel economy standard for trucks will be fuel burned per ton of freight hauled at (i think) 75% capacity - so a larger truck won't have a penalty as long as it can haul more freight.

On the other hand, you have two factors in play here. One, as discussed above, is the "real truck" buyers, who (just like their oversized pickup-driving counterparts) are willing to pay the extra fuel cost for a truck that looks "tough" and "manly".

Second, once you have a significant market for those advanced systems, they get mass-produced, and the cost falls, just as with EFI & turbos on passenger cars. But unless there's some impetus to mass produce them, they remain expensive specialty items that few people buy.

The biggest improvement to FE in big rigs is a 60 MPH governor. I just did a cross-country drive from California to Tennessee and back, and I can't tell you how many trucks passed me doing 80+ MPH.

In fact, I never gave a second thought to California's 55 MPH limit for trucks until I tried driving 65 MPH in Arkansas. Those trucks pass you at a +15 MPH delta, even in heavy rain, and it's downright unsafe. As far as money goes, didn't somebody on this site do the calculations and determine that they actually make more money at 55 MPH than 70 MPH just because of the fuel savings?

BTW, MVT has been at it again:

http://img843.imageshack.us/img843/2...humbnailer.jpg

Innovative Fleet Installing 3,500 Sets of Trailer Aero Improvers - Truckinginfo.com

Most of them are now sporting the Trailer Tail. Of course, they were driving 70+ MPH, too.

Yeah, there are always going to be people out there who are going to be stupid, but you don't need to outlaw stupid. Natural forces have a tendency to take care of that. If trucking company A spends thousands and thousands more on fuel than trucking company B, company B will have higher profits and grow. company A will loose money and eventually go bankrupt.

There is an impetus to mass produce them: profit. If a company can come up with a better technology and come up with a way to make it affordable then they will gain an advantage over they're lower-tech copmpetitors and make more money. Look at what's happened with Detroit Diesel's new DD15 engine with a turbo compound. It gets better FE than competitors and their market share is increasing.