Real time feedback on the impact of our actions: the instant MPG readout

I recently spent some time with my in-laws and drove their car for a few days. I was struck by the effectiveness of a small information display on the dashboard which often gets little attention, but has implications that go way beyond the context of the vehicle.

At any given instance during our daily routines, we make decisions that directly translate into more or less energy consumption and emissions, be it when we decide between using a car or a bicycle for a trip, or when we open a room window for cooling instead of air conditioning. But things are more nuanced than that. The technology systems that pervade our environment and provide various kinds of services and functionalities have grown increasingly complex. It can be difficult to understand how exactly our actions impact energy or resource consumption and emissions. Consider a room that you frequently sit in, it is often unclear what action would effectively reduce the energy consumption of that room while maintaining comfort: turn down the thermostat by 1 degree, close the room door to avoid draft, open the curtains to allow the sun to warm up the interior, or switch off one of the lamps?

Without a concrete understanding of the impact of our behavior and our actions, attempting to reduce our energy and emissions footprint remains an abstract exercise based on generic notions and little engagement. Increasingly, though, the systems and devices we use to support our actions generate digital data that can be used to make this more transparent. And there is that one particularly effective information tool in the middle of some car dashboards that addresses this challenge exceptionally well.

Now, there has been much talk about dashboards in the realm of data visualization and data driven information systems. The dashboard has evolved since its namesake origin as a wooden board on horse carriages that protected the carriage driver from mud or other dirt splashed up by the horses. In motorized vehicles the dashboard includes a combination of gauges that indicate relevant measures of the vehicle performance for safe operation. The dashboard has also been taken as a metaphor for the representation of urban data in the smart city discourse: city dashboards abound with a somewhat arbitrary combination of metrics visually displayed. While this delights mayors’ communication officers to signal that the administration is ‘in charge’ and ’controlling and steering the city’, it probably oversimplifies and confuses the complex and organic nature of cities, but that is a different story.

In all the focus on dashboards, what receives little attention is the one element that really does help each individual driver inform and change his behavior in a way to reduce the impact on fuel consumption and emissions: the instant MPG (miles per gallon) read out. The instant MPG readout, also known as an instant fuel consumption display or instant fuel economy gauge, in some cars utilizes information about the engine speed, rate of fuel-flow as well as different pressure and throttle positions. The car’s board computer processes this data to calculate an instant MPG result, which is then visually represented on the dashboard. The instant MPG readout differs from the more commonly found average fuel economy indicators that calculate an over time fuel consumption. The key in the instant MPG readout is that it reflects the impact of a driver’s driving style in real time, providing an effective tool for the driver to adjust his driving style. The harder or more gently you accelerate from a stop sign at a traffic light, the more aggressive your driving style overall, you immediately see how your driving translates into fuel consumption which allows you to make adjustments.

The history of this small yet effective device goes back to an invention by the Ford Motor Company in 1976 and which is based on patents from 1975 (Driver training and gasoline saving device) and as early as 1955 (Engine performance meter). Only recently did the instant MPG readout see a wider diffusion in conventional cars and in particular in hybrid cars where it speaks to an eco-conscious audience. The measures are represented in many different ways ranging from straight forward numbers or bar charts, to fancy trees that grow leaves as you improve fuel efficient driving. To describe the self-training of driving style using an instant MPG readout the term ‘eco-driving’ was coined around which an active ‘hypermiling’ community formed, drivers trying to squeeze out as many miles per gallon from their cars as possible by driving in fuel efficient ways.

Some studies [1,2] have analyzed the actual change in behavior in drivers using such instant MPG readouts and assessed their impact on fuel consumption. The studies found different results in terms of actual savings in the range of 1-6% as well as in percentage of study participants that did show change in behavior. Challenges of these studies lie in comparing before/after situations in a real world environment where many other factors play into a car’s fuel consumption as well as the attention and interest in the MPG readouts for driving adjustment over longer time periods. Overall, though, all studies conclude that having access to information about the real time impact of fuel consumption in cars does change driving behavior, and it does so – and that is no small feat – at no or minimum additional cost.

Now, how does that matter to us?

If we have such an effective tool in a complex engineering environment such as the car, I would like to see equivalent tools for other situations where our behavior and choices directly determine energy consumption and emissions generation.

The thermostat in my room where I set the desired temperature should tell me what my change in setting means in terms of energy consumption (for hot water generation in the heating circuit, powering the fans to circulate the hot air into my room,…). I might decide that keeping the same temperature and opening a window, putting a sweater on in the winter, or a lighter shirt in the summer works just fine to provide me with an equivalent comfort level while saving on energy and emissions.

I am thinking of kitchen appliances such as an oven or microwave in the kitchen, or hairdryer in the bathroom. The settings we choose on these appliances together with use duration determine very different amounts of energy consumption. Being aware of the quantified energy impact of our choices would allow us to make better-informed decisions.

When opening the water tap to wash hands, shower, or to rinse vegetable or fruit, the information about my instant level of consumption would provide the base for an immediate cost/benefit evaluation and translate into a more conscious behavior and potentially changed use patterns. Some interesting first steps to this point have been taken here and here.

Taking this further, the instant information about the energy impact can translate into $/minute of use or $/mile of a trip. This is essentially what is implicitly happening with instant MPG gauges in cars for the fact that drivers tend be aware of the per gallon price of gas. In either case, it is this drawing of connections between the actions we take and their impact that becomes a powerful tool. And this represents a growing opportunity for the design of data driven information systems that can shed more light into the consequences of our behavior in a complex environment.

And reconnecting to where I began, this also goes to show that you never stop learning when spending time with your in-laws…


[1] Boriboonsomsin, K., Vu, A., & Barth, M. (2010). Eco-driving: pilot evaluation of driving behavior changes among US drivers. University of California Transportation Center.
[2] Martin, E., Boriboonsomsin, K., Chan, N., Williams, N., Shaheen, S. A., & Barth, M. (2013, January). Dynamic ecodriving in Northern California: A Study of survey and vehicle operations data from an ecodriving feedback device. In 92nd Annual Meeting of the Transportation Research Board, Washington, DC, January.