In our November 2012 cover story, we looked at the fuel efficiency of the new Tier 4i-compliant row-crop tractors over 150 hp. For this latest round of testing, the Nebraska Tractor Test Lab (NTTL), the official testing lab, had to revise its testing procedures to account for the extra fuel and fluids needed to meet the mandated 90% reduction of particulate matter also known as soot, and a 50% drop in oxides of nitrogen, which forms smog.

The resulting “fluid” efficiency ratings (which factor in both fuel and fluids) ranged from 15.296 Hp-hr/gal to 13.058 Hp-hr/gal. As with previous fuel efficiency tests the higher the number is, the better the tractor is on fuel and fluids. Assuming that diesel fuel is priced around $4/gal. and diesel exhaust fluid (DEF) is priced similarly, a difference of 1 hp-hr./gal. in “fluid” consumption (i.e., both fuel and fluid) can mean a $1,300 difference in total fuel costs over the course of a year, according to the NTTL.

Please note:At the time of this report, only John Deere, Case IH, and New Holland tractors had been tested. The results of other makes and models will be released later this year. Also, note that fuel and fluid efficiency ratings for the story were based on “Drawbar Performance” at 75% of pull at maximum power to reflect performance during typical heavy fieldwork. But, as the story pointed out, ratings will vary according to the intended use of the tractor, so readers are advised to consider all operating points in the test when making comparisons.

Case IH underscores the potential for variance in the following official statements:

•             In the study, tractors are run at a steady operating load at maximum power and at 75% of maximum power, so while the resulting numbers are correct, they are not always representative of machine performance under typical agricultural operation.

•             DEF consumption is heavily dependent upon operational duty cycle, changing horsepower requirements, temperature, and humidity.  DEF consumption in production agriculture applications will typically be lower, on average, than constant pull testing cycles.

•             Fluid efficiency calculations and cost per hour referenced in the article assume an equivalent price for DEF and diesel fuel.  In reality, the national average price for DEF is currently about $2.80/gallon, considerably lower than the national average price for diesel.  The price differential should be taken into account when calculating total operating costs.

•             Typical lab test results typically reflect cost per hour only as it relates to the consumption of operating fluids relative to horsepower produced.  While this is an excellent litmus test, producers should consider the many other operating efficiencies of today’s models when comparing the various engine technologies available in ag tractors today.

-Case IH