In the United States (USA), transportation is the largest single source of
greenhouse gas (GHG) emissions, representing 27% of total GHGs emitted in 2020.
Eighty-three percent of these came from road transport, and 57% from light-duty
vehicles (LDVs). Internal combustion engine (ICE) vehicles, which still form the
bulk of the United States (US) fleet, struggle to meet climate change targets.
Despite increasingly stringent regulatory mechanisms and technology
improvements, only three US states have been able to reduce their transport
emissions to the target of below 1990 levels. Fifteen states have made some
headway to within 10% of their 1990 baseline. Largely, however, it appears that
current strategies are not generating effective results.
Current climate-change mitigation measures in road transport tend to be
predominantly technological. One of the most popular measures in the USA is
fleet electrification, receiving regulatory and fiscal encouragement from 45 US
states and federal bills. However, zero-emission vehicles (ZEVs) might not be
the climate change panacea for the transport sector. ZEVs are facing adoption
issues ranging from affordability, equity, and charging infrastructure to
vehicle class availability limitations. Despite increasing sales, US electric
vehicle (EV) adoption has been behind the curve with a current market
penetration of 4.5%. Outside of ZEVs, emission reduction in the US road
transport sector has been sluggish.
In road transport, which contributes the bulk of traffic-related air pollution
(TRAP), there are clear gaps between policy targets, technology-based
expectations, and actual results. For a sector that is struggling to meet
climate change targets, broadening its scope of climate change mitigation
measures for road transport would be useful. Driver behavior may be an
underexplored strategy.
Eco-driving is a known strategy and has been attributed to reducing TRAP by up to
50% (through nontechnological means) in various studies in the USA and across
the world. If technological eco-driving measures are included, they can improve
fuel economy in excess of 100%. But the extent to which it is included in driver
education and licensing protocols in US states is unclear.
This study, therefore, evaluates eco-driving in state-sponsored non-commercial
Driving License Manuals (DLMs). Provisions in state DLMs were assessed based on
the intent of the prescribed practices (collision safety,
environmental exposure, or both), the extent to which these
were included, and the strength of the recommended mechanisms
(prescriptive or regulatory). The scores were converted into Grades A–D.
The results are revealing. Despite thirty-three US states (66%) with extant
climate change commitments, almost the same percentage (62%) of states received
a “D” grade and entirely omitted to mention driver influence on fuel consumption
and emissions. Only five states (10%) received an “A” grade with substantive
eco-driving measures in their DLMs. There is thus significant scope for
eco-driving content in DLMs, which can range from the state’s communicating
climate change commitments to how drivers influence fuel consumption through
their driving practices to empowering drivers with strategies they can adopt to
save fuel and money and reduce emissions.
This inclusion has the potential to improve vehicular fuel economy and help
states meet their climate change goals. Driver education is the first step.
Eco-driving principles can be further bolstered through subsequent inclusion in
the driver training and testing phases of driver licensing.
