Eco-Driving: Simple techniques for operational savings

Three fundamental factors affect a vehicle's fuel consumption: the vehicle, driving conditions, which are outside the control of the driver and vehicle, and driver operation. Simply by having a driver practice fuel conservation driving habits, significant operational savings can be achieved.

In the Japan market, vehicle operating costs account for one-third of a company's overhead. About three-fourths of that is attributable to fuel costs.

Believing myself to be a fuel-conscious driver, I was excited by the opportunity to participate in an Isuzu Motors' Ecology and Economy Drive program at the manufacturer's Wacom proving grounds in Hokkaido, Japan. Hokkaido is the second largest, northernmost, and least developed of Japan's four main islands.

This particular event, conducted for a select group of North American truck trade journalists, was designed to demonstrate that focusing on specific key driving areas can appreciably reduce fuel consumption.

Isuzu Motors' findings show that drivers could cut fuel costs by up to 40%. This is based on average fuel economy improvements from its many interactive fuel efficiency seminars held in Japan since 1995.

To be honest, I wasn't expecting to gain much of an improvement. I routinely use fuel-saving methods, especially when I trailer-truck.

Being watched

Arriving at the Wacom proving grounds, we were given instructions on how to drive the 4.4 kilometer (approximately 2.8 miles) course, set up to mimic highway, stop-and-go, and inter-city driving. We were told our driving would be monitored by Isuzu Motor's Mimamori telematics fleet management system, designed especially for commercial vehicles.

Through the comprehensive use of GPS wireless communications based system, and ICT (information and communication technology), the Mimamori system provides real-time access to driving status. It would be monitoring our fuel consumption, vehicle speed, braking, gear use, and engine rpm preceding gear shifts.

First run

We were assigned a truck and told to drive as we normally would.

We all drove a similarly spec'd 136-inch wheelbase Isuzu ELF (the low cab forward N Series in the US) with a gvw of 13,650 pounds. The power-assisted steering trucks were powered by a 150 horsepower 4-cylinder Isuzu diesel backed to an Isuzu 6-speed manual transmission.

For me, a big test came at the start of my initial drive — getting used to right-hand drive with the shifter on the left.

Shortly after finishing our first run, we were given a diagnosis report of our driving from the Mimamori system. The report evaluated us on five driving techniques: vehicle speed in ordinary driving, engine speed in gear upshift, selection of optimal cruising gear ratio, degree of accelerator depression, and brake application.

Additionally, the report provided an overall evaluation score, along with driving technique suggestions for fuel economy improvement.

According to my diagnostic report, I started out too “aggressively,” didn't shift soon enough, and braked too hard a little too often. (Surely that couldn't be right. I wondered when the Mimamori system was last calibrated.)

The next step in the “Eco-Driving” program was a detailed classroom session on the whole matter of fuel consumption and conservation. Among the chief points made during the session:

When traveling on a highway, fuel economy can be improved by 12% or more each time speed is reduced between 5 to 10 miles per hour.
Avoid jackrabbit starts. From a full stop, gradually depressing the accelerator pedal allows the transmission to shift into the next gear at lower rpm, decreasing fuel consumption, particularly in stop-and-go situations.
Maintaining a steady, consistent highway speed reduces the need for frequent acceleration and deceleration, which increases fuel consumption.
Avoid excessive use of the exhaust brake. Turn it off and plan decelerations in advance, whenever possible. It is better to use engine braking alone. While it requires a longer distance to slow the truck, no fuel is consumed.
Keep idling to the minimum necessary.

Second run

Incorporating these simple fuel-conscious driving techniques into everyday driving habits can translate into substantial savings, we were told. Tests have shown that a truck averaging 35,000 miles annually could reduce fuel consumption by more than 1,200 gallons using the techniques.

At $4 per gallon for diesel fuel, that would translate into a savings of $4,800 per truck per year. For a fleet of 10 trucks, the savings would be $48,000.

Class over, we returned to our same trucks and ran the course a second time using what we learned.

Being very focused in my efforts, I recorded an overall fuel economy improvement of more than 30%.

And I thought I was effective at squeezing more mpgs out of every tank.