Ask the Driver

Updated: Jul 21

How to measure the true miles per gallon, emissions and horsepower for long-haul trucks

Vanessa, Data Manager and Test Driver for SPI.Systems Corporation, has more than 20 years of Class 8 driving experience. From long-haul to local, oversized and max weight, she has moved all kinds of freight.

SPI.Systems Corporation designs and sells the SPIER System, an upfit product for diesel trucks that saves fuel and cuts emissions, while also generating more power. With fuel prices soaring, we're all feeling the pain at the pump. Anything we can do to save even a few miles per gallon can result in significant bottom-line savings. Cutting emissions is always top of mind as the transportation and logistics industry is faced with ever-increasing government mandates, plus, being environmentally responsible is the right thing to do for the planet and for future generations. As always for the driver, reliable and adequate power availability is super-important. Few things are worse than not being able to climb hills at a decent rate of speed. I get excited about any technology that boosts power and acceleration, regardless of the terrain.

My job is to present specific data to prove that the SPIER System works. I use state-of-the-art telematic tools to measure liquid fuel consumption as well as my decades of experience as a driver. For example, for my test drive of a Freightliner Cascadia with a Detroit DD13 engine, I conducted repeated road tests of an OEM configuration vs. a SPIER-equipped rigging. We selected an interstate highway route on which we ran repeated road tests at a standard speed, typically 65 mph. We also tracked terrain variations. The comparative tests of OEM vs. SPIER were run on the same route, back-to-back, by the same driver for consistency.

The telematic tool serves as an additional data source to confirm the liquid fuel readings. We like the Freightliner DiagnosticLink because it is from the engineering teams at Freightliner and Detroit Diesel, who are widely recognized as leaders in their field. We also track torque variations vs. terrain and match them to the first data set to get precise MPGs at the same terrains and torques. Let’s see how they correlate.

Results Summary

Fuel Economy with SPIER, average of 2 runs 11.025 MPG

OEM 8.9 SPIER Improvement 23%

NOx at Engine-out with SPIER 578 ppm

NOx at Engine-out OEM 734 ppm

SPIER Improvement 21%

EGR % Open with SPIER 49%

EGR % Open OEM 65%

SPIER Improvement 25%

The data capture the essence of three years of SPIER development. It accounts for all the key variables associated with measuring fuel economy, emissions and horsepower and includes a mix of 4 engine makes, five chassis models, two exhaust configurations, terrains ranging from flat to 6,424-foot mountains, and ambient temperatures from 10 to 88F. All data are for trucks pulling loads of 35-50,000 lbs.

Bottom line? Our reporting proves that SPIER works! It delivers major improvements to the diesel combustion process, which translate to significant cost savings, environmental benefits, and happier drivers – all of which are a powerful business case for fleet owners to consider adopting this exciting innovative technology. But don’t just take my word for it. Look at the data, and always “ask the driver”😉

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