Introduction: Nashville’s Path to a Greener Fleet

Nashville, Tennessee, has committed to cutting its carbon emissions in half by 2030, a target that demands bold action across all sectors—especially transportation, which accounts for nearly a third of the city’s greenhouse gas output. While electric vehicles dominate headlines, another proven technology offers immediate, cost-effective emission reductions: flex fuel vehicles (FFVs). These gasoline-ethanol hybrids can run on any blend from pure gasoline up to E85 (85% ethanol), and they represent a strategic tool for Nashville to accelerate its climate progress without waiting for a full EV infrastructure build-out. By expanding FFV adoption in municipal fleets and among residents, Nashville can leverage existing ethanol production capacity, reduce petroleum consumption, and support local agriculture—all while making measurable strides toward its climate goals.

What Are Flex Fuel Vehicles?

Flex fuel vehicles are specially designed automobiles that can operate on gasoline, ethanol blends, or any mixture of the two. Unlike traditional vehicles, FFVs are equipped with sensors that detect the ethanol content in the fuel and automatically adjust the engine’s air-fuel ratio, ignition timing, and fuel injection to optimize performance. This seamless adaptability means drivers can fill up with regular gasoline, E85, or anything in between without any modification to the vehicle.

Ethanol, the primary renewable component in FFV fuel, is a biofuel produced by fermenting plant sugars—most commonly from corn in the United States. E85 contains 51% to 83% ethanol, depending on season and geography; in colder months, the ethanol content is reduced to ensure cold starts. While ethanol has about 30% less energy per gallon than gasoline, FFV engines are tuned to compensate, and the higher octane rating of ethanol can improve engine efficiency in certain driving conditions.

FFVs have been on the market for decades, with major automakers like Ford, General Motors, Chrysler, and Toyota producing millions of units. They are visually identical to their gasoline-only counterparts and are often sold at no additional cost. Many drivers may unknowingly own an FFV—look for a yellow fuel cap or a badge that reads “FlexFuel,” “E85,” or “FFV.” According to the U.S. Department of Energy’s Alternative Fuels Data Center, there are more than 20 million FFVs on American roads today.

The Role of Ethanol: Production and Environmental Impact

How Ethanol Is Made

Ethanol is produced through a process similar to brewing beer: starch from corn (or other feedstocks) is ground, cooked, and fermented with yeast to produce alcohol. The resulting ethanol is then distilled to fuel-grade purity (around 200 proof) and denatured to make it unfit for drinking. A typical corn-based ethanol plant also produces distillers grains, a high-protein livestock feed, and captures carbon dioxide for use in carbonated beverages or dry ice.

Beyond corn, second-generation cellulosic ethanol from agricultural residues, wood chips, and dedicated energy crops offers even greater greenhouse gas reductions. Although cellulosic production remains small-scale, ongoing research points to a future where ethanol can achieve up to an 86% carbon reduction compared to gasoline, when considering land-use changes and lifecycle emissions.

Lifecycle Emissions: Ethanol vs. Gasoline

The environmental benefit of ethanol depends on the fuel’s full lifecycle—from growing the crops to burning it in an engine. The U.S. Department of Energy’s Argonne National Laboratory calculates that corn-based ethanol reduces greenhouse gas emissions by roughly 40% to 50% compared to gasoline when using modern farming and production methods. Cellulosic ethanol can push that reduction to over 80%. These numbers factor in the carbon absorbed by the plants during growth, the energy used to produce fertilizer and run distilleries, and the transportation of the finished fuel.

It’s important to note that not all ethanol is created equal. The Environmental Protection Agency notes that the Renewable Fuel Standard sets specific lifecycle greenhouse gas thresholds that each category of renewable fuel must meet. E85 from corn ethanol qualifies as an advanced biofuel in some scenarios, and cellulosic ethanol is classified as a cellulosic biofuel with the highest emission reduction requirements.

Environmental Trade-Offs

Critics point out that large-scale corn ethanol production can have adverse effects, including fertilizer runoff, water consumption, and competition with food crops. However, improvements in precision agriculture, no-till farming, and cover cropping have significantly reduced the environmental footprint per bushel of corn. Moreover, many ethanol plants now use natural gas instead of coal for process heat, and some capture and sequester carbon dioxide from fermentation. The key for Nashville and other cities is to source ethanol from suppliers that prioritize sustainable practices and to support the development of advanced, cellulosic ethanol as it becomes commercially viable.

Nashville’s Climate Action Goals and the Transportation Sector

The Metropolitan Government of Nashville and Davidson County adopted its second Climate Action Plan in 2021, setting a target to reduce community-wide greenhouse gas emissions 50% by 2030 from a 2014 baseline. The plan identifies transportation as the largest source of emissions, contributing 30% of the total. To meet its goal, Nashville must reduce transportation emissions by more than 900,000 metric tons of CO₂ equivalent by 2030.

While electric vehicles are a critical long-term solution, the current pace of EV adoption in Middle Tennessee—coupled with limited charging infrastructure and higher upfront costs—means that other strategies are needed in the near term. Flex fuel vehicles offer an immediate, low-cost way to cut emissions from the existing vehicle fleet. Even a partial switch from gasoline to E85 can reduce tailpipe CO₂ emissions by up to 40% on a lifecycle basis, according to data from the U.S. Department of Energy.

Current Flex Fuel Infrastructure in Nashville

As of 2024, Nashville has approximately six public E85 fueling stations, concentrated along interstates and in a few suburban areas. While that number is modest, it represents a growing network. With municipal support—such as zoning incentives for station owners and streamlined permitting for ethanol dispensers—Nashville could rapidly expand E85 availability, particularly along major commuter corridors and near city-owned fleet depots. The city’s own fleet, including police cars, sanitation trucks, and public works vehicles, could be a lead user to jump-start demand.

How FFVs Contribute to Emission Reductions

To understand the potential impact, consider this scenario: If Nashville replaced 20% of the gasoline used by its light-duty vehicle fleet (approximately 50 million gallons annually) with E85, the resulting lifecycle CO₂ reduction would exceed 60,000 metric tons per year. That’s equivalent to taking over 12,000 passenger vehicles off the road permanently. When city fleets alone can achieve such savings, the case for encouraging wider FFV adoption becomes clear.

Moreover, ethanol’s higher oxygen content reduces particulate matter and carbon monoxide emissions, improving local air quality—a critical concern in a city that often experiences summer ozone alerts. This dual benefit of climate and public health makes FFVs especially attractive for a growing urban center like Nashville.

Implementation Strategies for Nashville

Municipal Fleet Conversion

The fastest way to deploy FFVs is to direct city fleet procurement toward these vehicles. Many police cruisers, pickup trucks, and vans already come in FFV versions from manufacturers. By specifying FFV in every new vehicle purchase where available, Nashville can convert a significant portion of its municipal fleet within five years. The incremental cost is zero or minimal, while the fuel savings from E85 (which often costs 20-40 cents less per gallon than regular gasoline) can be reinvested into additional climate programs.

Incentives for Residents and Businesses

To encourage private adoption, Nashville can offer a one-time rebate for new FFV purchases, similar to existing EV rebates. Local partnerships with auto dealers could promote FFV models through a “Green Mile” campaign, highlighting fuel savings and environmental benefits. Businesses with large fleets—delivery companies, ride-share operators, construction firms—could receive priority access to city-funded E85 fueling stations in exchange for committing to a minimum ethanol blend usage.

Infrastructure Expansion

The city can use its zoning authority to require new gas stations to include at least one E85 dispenser, or offer fast-track permitting for stations that add ethanol pumps. Public-private partnerships with ethanol distributors could fund the installation of new pumps at no cost to station owners, with the city guaranteeing a certain volume of fuel purchases from its own fleet to de-risk the investment. The Nashville Climate Action Plan specifically calls for increasing alternative fuel infrastructure, and FFVs align directly with that goal.

Education and Outreach

Many Nashvillians may not know that their vehicle is already flex fuel capable. A simple public awareness campaign—using social media, utility bill inserts, and signage at city offices—could ask drivers to check their fuel cap or owner’s manual. For new car buyers, the city could partner with the Tennessee Automobile Dealers Association to ensure each sale includes information on local E85 stations. School programs could teach students about corn-to-fuel science, linking agriculture and renewable energy.

Challenges and Considerations

No solution is without its hurdles. E85 typically offers lower fuel economy than gasoline—about 15% to 20% fewer miles per gallon—because ethanol contains less energy by volume. Drivers need to weigh this against the lower price per gallon. However, lifecycle analysis shows that even with reduced fuel economy, the net CO₂ reduction per mile remains substantial because ethanol’s production-phase emissions are much lower.

Another challenge is the “food vs. fuel” debate. While some argue that using corn for fuel drives up food prices, studies from the USDA and academic economists have found that the impact is modest and highly dependent on global commodity markets. The U.S. ethanol industry’s ability to produce both fuel and livestock feed from a single bushel of corn actually increases overall resource efficiency. Nashville could choose to source ethanol from producers that use cellulosic feedstocks or from those with certified sustainable farming practices.

Geographic variability also matters: Tennessee grows a significant amount of corn, but most of the state’s ethanol is produced in the Midwest. Transporting ethanol by rail or truck adds emissions and cost. A more resilient local supply chain—perhaps using sweet sorghum or switchgrass as feedstocks—could be a long-term goal for the region.

Comparing FFVs to Other Alternative Fuels

Electric Vehicles (EVs)

EVs are highly efficient and can achieve zero tailpipe emissions, but their upfront cost, charging infrastructure gaps, and battery material supply chains present barriers. FFVs, by contrast, use existing refueling stations (with relatively minor modifications) and cost no more than standard vehicles. For Nashville’s decarbonization strategy, FFVs can serve as a bridge technology while the grid becomes cleaner and EV adoption scales up. In fact, many fleet managers are using both—adding EVs for short, predictable routes and FFVs for long-haul or high-utilization vehicles.

Biodiesel and Renewable Diesel

For heavy-duty trucks and buses, biodiesel and renewable diesel offer similar lifecycle CO₂ reductions. However, these fuels require specialized engines or modifications, while FFVs require no changes. Biodiesel also faces cold-weather gelling issues that E85 does not. Still, a diversified approach that includes both ethanol and biodiesel can maximize overall fleet emission reductions.

Compressed Natural Gas (CNG)

CNG vehicles produce lower tailpipe CO₂ than gasoline but still rely on fossil fuel extraction. The infrastructure cost for CNG stations is high, and the vehicles themselves are more expensive. FFVs offer a lower entry barrier for both drivers and the city.

Conclusion: A Practical Step Forward

Nashville’s climate goals are ambitious, but achievable through a portfolio of solutions. Flex fuel vehicles are not a silver bullet—they are a proven, cost-effective tool that can deliver real emission reductions in the near term without requiring massive infrastructure investments or behavioral changes. By prioritizing FFVs in municipal fleets, incentivizing private adoption, expanding E85 fueling stations, and educating the public, Nashville can make tangible progress toward its 2030 target. The path to net-zero runs through multiple technologies; FFVs deserve a prominent place in that journey.