For passenger cars and light trucks the numbers are really stunning. From the current 27.5 mpg CAFE requirement, the average fuel economy mandated for the 2016 model year is 35.5 mpg. The story continues with proposals for 2025 that range from 47 to 62 mpg. Given time to think things over, it seems likely that the federal government (not to mention states such as California) will aim even higher.

For the heavy-duty market, there is no doubt that changes are coming, including emissions reductions beyond what is current. The federal Environmental Protection Agencys website spells out the plans in some detail. However, the appropriate method of measuring fuel economy improvement is still being debated.

EPA and the National Highway Traffic Safety Administration are proposing new standards for three categories of heavy trucks: 1) combination tractors, or semi-trucks, 2) heavy-duty pickups and vans, and 3) vocational vehicles. These categories were established to address specific challenges for manufacturers in each area. Here are the schemes for each:

Engines for combination tractors: Beginning with the 2014 model year, these vehicles must cut emissions of carbon dioxide (grams of CO2 per ton-mile) by up to 20 percent and also reduce average fuel consumption by that amount by the 2018 model year. (See Table 1.)

Heavy-duty pickup trucks and vans: The agencies propose to establish CAFE standards for heavy-duty pickup trucks and vans, similar to the approach taken for light-duty vehicles. Separate gasoline and diesel truck standards will phase in, starting with the 2014 model year. They must achieve up to a 10 percent reduction in fuel consumption for gasoline vehicles and 15 percent reduction for diesel vehicles by the 2018 model year (or 12 and 17 percent, respectively, if accounting for air-conditioning leakage).

Vocational vehicles: These include purpose-built workhorses such as refuse, delivery and utility trucks, cement mixers, snowplows, school and municipal buses, etc. Standards start with the 2014 model year and should achieve up to a 10 percent reduction in fuel consumption and CO2 emissions by the 2018 model year. (Table 2)

Note that in all cases fuel economy is being reported in gallons consumed per 1,000 ton-miles. This is in recognition of the fact that in this market, how much cargo is moved is more important than mere miles per gallon.

These proposals give the heavy-duty and vocational markets seven years to improve fuel economy (and CO2 emissions). That isnt a lot of time, when vehicle and engine design changes might not be easy to come by.

Grading Vehicles

Highlighting the new interest in boosting fuel economy, the EPA also has proposed three new designs for new vehicle stickers showing fuel economy. One design would grade vehicles on their fuel savings (based on what is not clear); another stresses annual fuel costs; the third adds an environmental rating. Page 6 shows examples suggested for gasoline and diesel vehicles, and other samples can be seen at www.epa.gov/fueleconomy/label.htm.

New vehicles will be graded on both their fuel efficiency and CO2 emissions. Fuel efficiency will be compared to some average fuel consumption value, and savings or extra costs reported. Also note that fuel economy is being reported in gallons/100 miles as well as miles/gallon.

Obviously, lubricant requirements are going to change, as Ive discussed in earlier columns. The big movers for improved fuel economy in engine oils and transmission fluids are lower viscosity, friction modifiers and more protection against deposits and oxidation. To reduce emissions, engine oils will require strict catalyst compatibility as well as deposit control.

Were getting close to the limit on viscosity, in my opinion, as laid out in SAE J300, the document that defines the Engine Oil Viscosity Classification System. The SAE J300 Viscosity Task Force is contemplating new, low-vis grades with high-temperature, high-shear viscosity limits below 2.0 mPa.s (we used to call these cPs but no more). Base stock viscosities below 4 mm2/s (cSt for us old-timers) will be required to meet these new grades, especially for multi-vis products. (These changes were brought to my attention by Lubrizols Mike Covitch, secretary of the J300 task force.)

More use of synthetic base stocks is a sure thing with these proposed new viscosity grades, and that will mean more expensive oils, too.

Calculating Ton-miles

While were on the subject of fuel economy, I recently heard from Mary Ann Dahlstrom of Shell regarding the issues raised in my October column. The most recent article on HD lubricants was interesting, she wrote, but it calculated fuel economy for heavy-duty vehicles in gallons per ton-mile. It might have been interesting to include a comparison of a typical passenger vehicles fuel economy in that unit, she suggested, instead of the usual mpg.

Thats an excellent question. First, lets look at what the calculation is based on. Fuel economy in mpg can be easily converted to gal/mile simply by taking the inverse of the Fuel Economy number (i.e., 20 miles per gallon equals 1/20 gallon per mile). Next, that number is divided by the cargo tonnage value to get to gal/ton-mile, and then multiplied by 1,000 per the new designation proposed by EPA.

When you make a comparison of fuel economy on the basis of cargo weight (as in heavy-duty trucks), you have a pretty well-defined set of values with which to work. For passenger cars it is a bit more difficult but not impossible. The following is a calculation based on some assumptions using my own personal driving experience:

– Vehicle: 2008 Nissan Quest

– Average fuel economy: 23 mpg, calculated by on-board system

– Average cargo weight: 500 lbs. approximately. (My wife and I are usually the only ones in the vehicle plus luggage, golf clubs, etc.; and no, the two of us do not weigh a quarter-ton.)

– Gallons consumed per mile: 0.0435 gal/mi

– Gallons per 1,000 ton-mile: 43.5 gal

By comparison, Octobers column calculated average heavy-duty truck consumption at 0.003 gal/ton-mile or 3 gal/1,000 ton-mile. So it looks like trucks are way more efficient at hauling cargo than are passenger cars.

The Rail Option

In her note, Dahlstrom also pondered the future of heavy-duty hauling and the issue of road capacity for heavier loads. Is it more efficient to use railroads for long hauling, she asked, with intermediate-weight trucks to transfer load from the trains into metropolitan centers as a competitive scenario?

The question of railroad piggyback hauling is also a good one and worth a look as well. First, I turned to the Union Pacific for the following facts:

One intermodal train can carry 280 containers (probably 40- to 53-foot trailers).

If 10 percent of trucks were moved off the highway and onto the railroad as intermodal, it would save 200 million gallons of fuel annually.

One gallon of fuel moves one ton of rail cargo 406 miles.

On that basis, intermodal train hauling yields a fuel consumption of 2.5 gal/1,000 ton-mile.

When you compare this to a trucks 3 gallons consumed per 1,000 ton-miles, you can see that this is very competitive. The fact that railroad intermodal hauling removes trucks from highways is another benefit.

Now, to complete the story, once the cargo from the intermodal operation is received, it is moved into urban areas by truck. This still requires the use of heavy-duty bobtails, trucks without trailers. Youre still using the same rig systems that over-the-road haulers use, and there will still be large numbers of tractor-trailer combinations on the road in urban areas. Fuel economy for these systems is just 3 gal/1,000 ton-mile (or worse, since theyll operate mostly under stop-start conditions on congested, low-speed roads).

Dahlstrom and the rest of us can expect fuel economy to continue to make headlines, with new government regulations, new ways of reporting vehicle performance including new placards for designating fuel economy, and a continuing need to improve.

This makes for some exciting times for vehicle manufacturers, and indirectly for the oil industry. Well all need to be on our toes and straining for every droplet of fuel savings. Are we having fun yet?