There is a litany of terms moving around the navigation space right now in relation to the environmental impact of not only navigation devices, but also the data that empowers them. "Green driving." "Green routing." "Eco-routing." These concepts are all important to the future of helping the vehicles we produce, and the consumers who own them, be more environmentally friendly. And we're not talking too far in the future -- these concepts each already have a number of proof points behind them.

But understanding clearly the implication of each, and more importantly, how you can assess five distinct methods of greener driving on a continuum along which the experience can move, provides meaningful insights into how we can speak as an industry on the subject.

The Entry Point: The Navigation System

It may seem obvious, but the conversation starts with the addition of navigation to a vehicle. There has long been discussion about the impact of navigation on fuel efficiency in "getting lost" scenarios. In those cases the driver doesn't continue to wander in search of a destination, generating excess CO2 emissions in the process.

But in regions of the world like Western Europe, and more recently in the United States, where there are governmental regulations and monetary incentives to automobile manufacturers on the environmental impact of a vehicle, it becomes necessary to prove how navigation impacts driving on an everyday basis.

In my company's examination of research to date, we could find no study that provided a look at average drivers using navigation as part of their general driving habits, whether that be running errands, driving to work or taking children to school. So in 2008 we commissioned a project with NuStats, a social science research firm with established leadership in research pertaining to transportation and personal mobility, for that specific purpose.

The study was conducted in two metropolitan areas of Germany -- Dusseldorf and Munich -- and followed three groups of drivers: One group of drivers without a navigation system, one group of drivers who were provided a navigation device, and one group of drivers who were provided a navigation device enabled with real-time traffic.

All the participants' cars were fitted with a logging device which was used to track the routes they drove and their driving speeds. In total the study reflected more than 2,100 individual trips, over 20,000 kilometers of driving (equivalent to 12,000+ miles) and almost 500 hours of driving time.

The results point to a clear, positive environmental impact strictly through the regular use of a navigation system. The drivers with navigation (both with and without traffic) saw their fuel efficiency increase 12 percent, with their fuel consumption falling from 8.3 to 7.3 liters/100 kms. In the United States, this would be the equivalent of a car improving from 27 mpg to 30 mpg.

This increase in fuel economy seen among the study participants would translate to a decrease of .91 metric tons in CO2 emissions every year per driver -- a 24 percent decrease over the amount that the average non-navigation user emits each year. Based on another key finding from the study, that the participants with navigation drove less on average per trip, each of those drivers would travel nearly 2,500 kilometers less each year, saving 1.19 million tires from disposal in Germany alone.

Eco-Routing

Eco-routing is the next step along the continuum, and takes navigation efficiency one step further. This is defined as using a route calculated to minimize fuel consumption, so in this case we are talking about the actual navigation experience.

Currently, navigation systems calculate the shortest-time route from origin to destination. Some systems also allow for a shortest-distance calculation. With eco-routing, the system is asked to find the route with minimum fuel consumption.

There are factors such as slopes, start and stop sequences and speed changes that are known to impact fuel efficiency, and so the system will also use information from the digital map data behind the nav system to identify these factors, such as road slope, traffic, traffic lights and stop signs, city center designation, cross roads, curves and railroad crossings.

For each segment of road, it is possible for the navigation system to define a fuel consumption index based on both these map attributes as well as engine characteristics. This index used in combination with distance and estimated travel time can provide a calculation of the path of minimum fuel consumption -- the "green" route.

We put this concept to the test in a partnership with Magneti Marelli of Italy, by examining calculations comparing the "Fastest Route" to the "Greenest Route" under several scenarios ranging from Paris to Frankfurt to New York and Chicago (both city and suburban). There was at least a 5 percent fuel savings per trip, and often more. And the time penalty from the fastest route was on the order of a few minutes at worst. The first prototype of this type of "green" navigation system was previewed by Magneti Marelli at the Paris Motor Show in October 2008.

Green Driving

The concept of green Driving takes a step away from the actual navigation device, and moves into the area of driving behavior; in effect, guiding a vehicle following fuel-saving recommendations. But while this third technique does not require an actual calculated route as with a Nav system, again there is digital map data which comes into play.

To optimize fuel consumption, a car's speed needs to be adapted to the road profile and the car needs to maintain the most stable speed along its trip. Fuel is wasted by actions such as accelerating just before a curve, a roundabout or a limited speed zone such as a city center or school neighborhood, or by climbing a slope in the wrong gear. Digital map data can be used to allow for anticipation of these conditions thus minimizing the speed and gear changes on the trip.

The green driving system "looks ahead" down the road, identifying required speed changes and guiding the driver how to accelerate or brake most economically. The car will accelerate a little before the hill, and gradually decelerate as it climbs to stay in the highest gear longer. The driver is guided to brake gently well before a stop sign that might not even be visible yet, and the driver is informed not to accelerate with a curve coming up or intersection approaching.

With a manual transmission, a green driving system can even recommend the optimum gear when climbing a hill. This map foresight of the green driving system looks forward a mile or two down the road to identify key road attributes as one drives. The result is optimized fuel consumption by adapting the car's speed to the road profile ahead.

Again we collaborated with Magneti Marelli to look at the benefits of green driving. Estimates of fuel savings ranged from 5 percent to 15 percent for drivers who chose to follow the green driving recommendations.

Today some hybrid car models already have green driving displays that monitor the instantaneous demand on fuel consumption and efficiency of braking. Those systems analyze the driver's aggressiveness on the gas and brake pedals. With a map-based green driving system, drivers can have information well in advance of a speed change so that it is possible to drive smoothly, accelerate and decelerate gently, and keep as steady a speed as possible thus saving fuel and reducing emissions.

Predictive Cruise Control

Cruise control is of course not a new concept; on longer trips and on highways it is well known that cruise control will typically will help a driver maintain a constant speed and save fuel. However, this is not necessarily true in the presence of hills.

For example, a cruise control system may suddenly downshift while climbing a hill, when the driver can see that the crest of the hill is not far away and could easily be reached by just easing up on the gas a little and staying in a more efficient gear.

New Predictive Cruise Control Systems are coming into vehicles now, which again can use digital map data to "look ahead" and decide on the best throttle position and gear for the hill or even for a curve. This new path to greener driving is all the more important in an era where car and truck manufacturers are now deploying new multi-speed transmissions, with seven, eight or nine gears compared to traditional three or four speed automatic transmissions. These multi-speed transmissions will improve fuel economy and smoothness on their own, but now it will be even more important to anticipate hills and curves and find the right gear before it's needed.

Hybrid car owners, especially sensitive to fuel economy as one of the reasons they chose their vehicle in the first place, can also benefit greatly from a Predictive Cruise Control system. Some hybrid owners have noted that on longer trips they actually decrease fuel economy when engaging their traditional cruise control system compared to their savvier manual driving. A Predictive Cruise Control system can change that.

And studies have already shown that truckers might be able to save 3 percent or more on increased fuel economy, depending on road conditions, a figure not taken lightly in the heavy vehicle industry who has become an early adopter of Predictive Cruise Control. The Freightliner truck division of Daimler Trucks of North America released a Predictive Cruise Control system early in 2009.

Advancing Hybrid Technologies

The fifth and final method for enhancing fuel economy and reducing emissions is a complicated but important integration of digital maps: Green driving systems that “look forward” for the driver and the hybrid engine controller in a hybrid vehicle.

In the simplest terms, a hybrid attempts to use the electronic motor whenever possible, as long as the battery lasts, and to minimize the use of the internal combustion engine that uses fossil fuel. The hybrid controller must carefully monitor battery charge to make sure that the battery does not run completely out. For this reason, the hybrid controller is conservative to make sure the battery charge is not drained.

It is possible for the system to operate more intelligently when digital map data is brought into the picture. For example, if the system knew that there was a recharging opportunity on the downhill side, it could drain the battery lower while climbing uphill.

{related_content}Similarly, knowing that there are stop signs or other deceleration opportunities ahead, the system could plan on regenerative braking to add charge to the battery, and thereby regulate battery drain more effectively. Studies in the U.K. by Ricardo Corporation demonstrated hybrid vehicle fuel economy gains by 5 percent to over 12 percent using these techniques.

The Role Our Industry Plays

We've reached a point as an industry where it is not just about moving the conversation in this area forward, but the actual execution. We must continue to research and measure the effectiveness of green technologies in vehicles and evaluate the investment in data and technology necessary to achieve superior levels of fuel savings and emissions reductions.

Navigation system manufacturers must implement green navigation features and make their customers aware of these enhancements. Other players in the value chain, such as the makers of digital maps, like my company, NAVTEQ, also need to play a role.

For example, we developed a concept "Map and Positioning Engine," a small, inexpensive module with GPS, a map, and software that can enable Predictive Cruise Control and hybrid controller enhancement systems. This will allow car manufacturers and their system suppliers to seriously consider making this capability part of every car they build so that all drivers will have access to personal savings and preserving the environment. And finally, we all must build awareness among drivers that navigation -- in any form -- can help make their cars more eco-friendly.

While the research is coming in verifying these fuel and emissions savings technologies, it should be noted that there remains one major obstacle to mass adoption.

Governments throughout the world are quite appropriately legislating improved fuel economy and CO2 reductions. Automobile manufacturers will suffer stiff penalties for not meeting these standards. But while research has shown that navigation and digital maps, embedded in the vehicle, can contribute 5 percent, 15 percent and more to these goals, currently the governmental testing methods used to verify environmental standards compliance do not give any credit for the technologies discussed in this article.

The reason is that these gains rely on driver choices and driver behavior. The driver can choose, in most cases, to not use the system. While it is true that this mitigates the advantages that might accrue from diligent system use, it is also true that without granting some level of credit for implementing these systems, the incentive for implementing these techniques is being greatly diminished.

It's important to consider that if even half of the benefit is achieved because half of the drivers use the systems, then auto manufacturers should benefit from deploying these map-based green technologies, which may be more cost-effective for them than other complex engine modification designs.

The bottom line should be one of how our industry provides access to affordable technology that can enable drivers to contribute to cleaner air and to save some money as well. There is a role for all of us in pushing to achieve this goal.

Bob Denaro is the Vice President for NAVTEQ's initiative in Advanced Driver Assistance Systems (ADAS), responsible for building this market and business for the company, applying digital maps to automotive driver assistance, active safety, fuel economy and usage-based charging systems to enhance their performance and acceptability to drivers.

_{Photos CC-licensed by Flickr users David Salafia and Paulio Geordio.}