Not All EVs Are Green
When we picture electric vehicles, we imagine zero emissions—but the truth is, every EV mile still creates some CO₂, mostly from electricity generation. Since about 60% of U.S. electricity comes from fossil fuels, an EV’s real carbon footprint depends on how and where you charge it.
This project compares pure electric and pure gasoline vehicles (excluding hybrids) using EPA data, focusing on the top five automakers—BMW, Ford, GM, Mercedes-Benz, and Toyota—based on the number of models tested for EPA fuel economy. I analyzed how emissions differ by vehicle type, efficiency, manufacturer, and the electricity mix in each state.
Some of the Key Research Questions I am trying to answer are as follows:
On average, how much CO₂ is emitted when driving 10,000 miles in an EV vs. a gasoline car?
Electric vehicles promise cleaner driving, but just how much cleaner are they compared to gasoline cars?
How much cleaner are electric vehicles compared to gasoline cars? The headline stat is clear: across the U.S., EVs emit over 60% less CO₂ than their gasoline counterparts over 10,000 miles. This dramatic difference is a big reason EVs are hailed as a climate solution. But is the story really that simple? Let’s dig deeper.
This simple yet powerful bar chart compares the average CO₂ emissions of electric and gasoline vehicles over 10,000 miles of driving. Based on EPA 2023 data, the results are striking: gasoline cars emit an average of 3.30 tons of CO₂, while electric vehicles emit only 1.32 tons on average when accounting for emissions from electricity generation. This amounts to a 60% reduction in emissions when choosing an EV over a gasoline-powered vehicle. The tooltip provides added context—showing fuel type, average emissions, and number of models represented—helping users see the scale of impact for each fuel type. This visualization offers a clear, accessible argument for EV adoption based on measurable climate benefits.
While EVs dramatically lower emissions, the real story of their environmental impact is more complex.
Cleanliness of an EV depends not only on the vehicle, but also on where it’s charged.
This interactive map shows how much the electricity grid in each state shapes your EV’s real-world emissions. States that rely on renewables or cleaner energy give EV drivers a much smaller carbon footprint, while states that burn more coal make “clean” driving less clean than you might expect.
Use the map to see how your choice of state—and even your favorite brand—can change the true impact of going electric.
🤔 TASK: Which state gives your EV the cleanest charge?
This interactive U.S. map visualizes how the carbon intensity of state electricity grids influences electric vehicle (EV) emissions, depending on which brand you select. While EVs produce zero tailpipe emissions, they still contribute to CO₂ pollution through the electricity used to charge them—and this electricity is cleaner in some states than others. The darker the state, the higher the carbon emissions per kilowatt-hour of electricity generated there. When a specific manufacturer is selected from the dropdown (e.g., FOMOCO), the map updates to reflect how that brand’s EV models would perform across the U.S. based on regional energy sources. By hovering over any state, viewers can see the estimated CO₂ emissions per mile for EVs from the chosen brand, driven by that state’s electricity mix. This visualization highlights the regional complexity of EV sustainability and shows that the cleanliness of an EV depends not only on the vehicle, but also on where it’s charged.
The tooltip adds another layer of insight, displaying the estimated CO₂ emissions per mile for the selected brand’s EVs in a given state, along with the state’s grid carbon intensity. This gives users an easy way to compare how environmentally friendly the same car can be depending on where it’s charged—highlighting that your zip code can shape your carbon footprint even when driving electric.
The same EV can be dramatically cleaner or dirtier depending on the local energy grid. Your zip code matters as much as your car!
Not all car companies are moving at the same speed toward a cleaner future.
The charts below reveal how each brand’s mix of electric and gasoline models influences their emissions—and how horsepower changes the equation. Electric vehicles maintain low emissions across all performance levels. In contrast, gasoline vehicles get dirtier as engines get stronger—debunking the myth that clean driving means sacrificing power.
🤔 TASK: Click on each manufacturer in the chart to explore their emissions across vehicle horsepower. Who stands out? Any surprises?
This dashboard compares emissions performance across electric and gasoline vehicles. The top chart analyzes how CO₂ emissions relate to vehicle horsepower. It reveals that electric vehicles consistently produce low emissions across all horsepower levels, while gasoline vehicles show much greater variation, with emissions generally increasing as horsepower rises. This challenges the common belief that high performance must come at a high environmental cost—EVs prove it’s possible to have both power and low emissions. The bottom chart shifts the focus to manufacturers, showing what percentage of their total emissions comes from electric versus gasoline vehicles. While companies like Toyota and GM still rely heavily on gasoline cars, others like BMW and Mercedes-Benz have a higher share of EV-related emissions, suggesting a more active shift toward electrification. Together, these visualizations highlight the environmental benefits of EVs and expose how uneven progress toward lower emissions remains across the automotive industry.
Some manufacturers are turning to EV faster, while others still rely on gasoline. EVs break the link between horsepower and pollution.
Not all EVs are equally clean.
The chart below shows how much energy efficiency matters: every boost in MPGe (miles per gallon equivalent) cuts annual emissions. The most efficient EVs can emit less than 1.5 tons of CO₂ a year—even on a fossil-fuel-heavy grid.
🤔 TASK: Hover over each dot to spot the most and least efficient EVs. Can you find any surprises among well-known brands?
Efficiency amplifies the benefits of going electric. If you want the lowest carbon footprint, choose an EV with high MPGe—and a clean grid.
This scatter plot explores how the energy efficiency of electric vehicles (measured by MPGe) affects their annual carbon emissions. Each green dot represents a specific EV model, with the x-axis showing its MPGe and the y-axis showing its estimated CO₂ output over 10,000 miles. A clear trend emerges: vehicles with higher MPGe emit significantly less CO₂. For example, a Cadillac EV from GM with an MPGe of 89 emits about 1.33 tons of CO₂ annually—noticeably less than less efficient counterparts. The tooltip reveals key details for each model, allowing users to connect brand, performance, and emissions. This visualization highlights the importance of efficiency not just for saving energy, but for reducing a vehicle’s overall carbon footprint.
Going electric is a big step toward cleaner driving, but it’s only part of the solution. The true environmental impact depends on what you drive, how efficiently it uses energy, and—just as importantly—where you plug in. As grids get cleaner and manufacturers speed up the shift to electric, every choice we make can bring us closer to a low-carbon future.
This project combines multiple datasets to evaluate and visualize the CO₂ emissions of electric and gasoline vehicles across the United States. The analysis focuses on average emissions, vehicle efficiency, and regional energy grids to reveal how geography, fuel type, and manufacturer choices impact a vehicle’s carbon footprint.
Datasets Used
EPA eGRID 2023 Data
Source: EPA eGRID
Provides region-level and national carbon intensity data (g/kWh) for electricity generation across U.S. electric grid subregions.
EPA Fuel Economy & Emissions Data 2023
Source: FuelEconomy.gov
Offers CO₂ emissions (g/mi) and model details for gasoline and electric vehicles. Note: MPGe values for EVs were not always included, so I manually collected them for each EV model via FuelEconomy.gov to ensure accuracy.
To compare average emissions of EVs to gasoline vehicles across the U.S., we used the national average CO₂ intensity of electricity from the 2023 eGRID data: 349.96 g/kWh
Calculations
CO₂ per 10,000 Miles:
Gasoline: (CO₂ g/mi × 10,000) / 1,000,000
EV: ((10,000 × 33.7 / MPGe) × 349.96) / 1,000,000
EV Emissions by Region:
Used each state’s regional CO₂ emission factor (g/kWh) to adjust EV emissions:
((10,000 × 33.7) / MPGe) × [Regional CO₂ Intensity] / 1,000,000
(Data processing in Google Sheets, then visualized in Tableau.)
eGRID Subregion-to-State Mapping:
Matched each state to its eGRID subregion for accurate regional calculations.
Tableau: Primary visualization tool to create visualizations
Google Sheets: Used for data cleaning and preparation
This project could be further developed by incorporating financial comparisons, such as fuel cost estimates and state-level EV incentives, to connect environmental insights with everyday economic considerations. Adding personalization features—like an emissions calculator based on location and vehicle type—could make the tool more informative and accessible for individual users. Additionally, using real-time or seasonal grid data may allow for more accurate estimates of EV emissions, reflecting how electricity sources vary throughout the day or year.
Integrate Hybrid Vehicles
Expand the analysis to include hybrid and plug-in hybrid vehicles for a more complete picture of emissions across all powertrains.
Add Financial & Incentive Data
Incorporate fuel cost estimates and state-level EV incentives to link environmental insights with real-world economic considerations.
Enhance Personalization
Introduce a personalized emissions calculator and use real-time or seasonal grid data for more precise, user-specific results.
U.S. Energy Information Administration. Electricity in the U.S. 13 Mar. 2024, https://www.eia.gov/energyexplained/electricity/electricity-in-the-us.php.
U.S. Environmental Protection Agency. Data on Cars Used for Testing Fuel Economy 2023. U.S. Department of Energy, https://www.epa.gov/compliance-and-fuel-economy-data/data-cars-used-testing-fuel-economy. Accessed March 30th 2025.
United States Department of Energy and Environmental Protection Agency. Fuel Economy: Find and Compare Cars. 2023, https://www.fueleconomy.gov/feg/findacar.shtml.
United States Environmental Protection Agency. Emissions & Generation Resource Integrated Database (eGRID) – Detailed Data. 2023, https://www.epa.gov/egrid/detailed-data.
