When most people think about their car emissions, they tend to imagine personal vehicles, typically owned or leased, used for commuting, long-distance travel, and day-to-day trips, like the grocery store… not car rental carbon offsets.
All cars, including rentals, emit the same harmful greenhouse gases (GHGs) – and often, the same emission levels. Yet, you can dramatically reduce your annual emissions by switching to a rental instead of buying. Opting for low-emissions transportation options for daily commuting and saving the cars for longer trips could be the key to living a greener lifestyle.
Still, you’ll need to keep track of your mileage while driving a rental car to ensure you keep things carbon neutral. Only a handful of companies help their customers out with this, so you’ll need to learn how to do it yourself.
Car Emissions are Major Pollution Contributors
You’ve heard it a million times over: Cars release greenhouse gases at every stage of their lifetimes, from assembly to its time on the road to demolition. Passenger cars and other vehicles like pickup trucks accounted for 29 percent of the entire United States’ transportation sector emissions in 2019.1
Now, this category includes several types of vehicles, including:
Still, passenger cars, among other vehicles like sport utility vehicles (SUVs) and light-duty trucks, make up the bulk of this sector’s GHGs annually. The United States Environmental Protection Agency (EPA), stated that the following vehicles “account for over half of the emissions from the transportation sector:”1
- Passenger cars
- Light-, medium-, and heavy-duty trucks
- Pickup trucks
When you drive a car – rental or not – the fuel combustion releases gases such as methane (CH4), nitrous oxide (N2O), and hydrofluorocarbons (HFCs). Yet, rentals share the same flaws as owned or leased cars, making them more essential to climate-friendly transportation.
Some rental companies charge their customers per mile in addition to flat rental fees, enforce a daily mileage cap, or offer unlimited mileage with a premium rate. Thanks to the added costs, such policies can help incentivize less driving, thus reducing emissions per rental vehicle.
The Consequences of Tailpipe Emissions
Methane gases are of critical concern in the rapidly worsening climate condition. Researchers report that Earth’s natural mechanisms responsible for breaking down atmospheric methane are getting weaker, making the world much more susceptible to an increasingly warm climate.2
Methane emissions account for a staggering 40 percent of global warming since the Industrial Revolution. Though people often refer to carbon dioxide (CO2) as the most concerning GHG, methane is just as destructive, if not worse over time. According to the Climate & Clean Air Coalition (CCAC), it’s “86 times more powerful than carbon dioxide over a 20-year period.”3
On the other hand, N2O made up about 7% of all US GHGs in 2019. Like methane, these are highly destructive gases. This isn’t only because their warming is nearly 300 times that of CO2 pound-for-pound, but because they stay in the atmosphere for 114 years before something can remove or destroy them.4
Then there are HFCs. The EPA describes these as “potent greenhouse gases with high GWPs.” (GWP stands for “global warming potential.”) This is one of the gases that sticks with your vehicle through every stage of its life. HFCs are released during manufacturing processes and during the car’s use phase, when they’re released through leakage from the car’s air-conditioning system.4
These GHGs have seen one of the most dramatic increases in atmospheric over the past several decades. Experts report that HFC levels have risen by 275 percent since 1990, mainly because manufacturers switched to using HFCs instead of compounds that damage the ozone layer.4
All cars release these gases and more when driven, whether you’re renting it or bought it. Still, it’s so easy to brush off the miles you racked up in a rental versus a vehicle you own (especially if you drove it on a vacation or unusual trip). Because of this, you must keep track of your rental car miles. It’ll help ensure your lifestyle stays truly carbon-neutral.
Using Car Rental Carbon Offsets to Offset Your Miles
Rental car companies are starting to catch onto the fact that many drivers aspire for carbon neutrality. Yet, they rent to millions of people each year, and it’s tough to help that many people reach their goals. Still, some rental corporations have stepped up to the plate, such as Enterprise and Hertz.
In 2008, TerraPass and Enterprise struck up a partnership to help customers purchase a carbon offset to neutralize their miles in the company’s rental cars. They offered 300 lbs’ worth of carbon reduction for $1.25. One carbon offset would be able to offset the average rental period, ideally. Additionally, Enterprise offered to match offset purchases up to $1 million.5
This collaboration continues to this day with impressive progress, having offset a total of 77,157 metric tons of rental cars’ CO2 emissions. In 2020, Enterprise accumulated 15,709 metric tons (about 17,316 tons) worth of offsets, with 2019 being their record year at 21,384 metric tons (23,571 tons).6
Hertz Sweden has also extended rental car drivers a helping hand in reducing their carbon footprints. Their offset program, run in partnership with Zero Mission, a Swedish carbon offsetting company, pulls data from the vehicle database to inform customers of their emissions, so they know how much to offset.7
When drivers sign their rental lease, they’ll have the opportunity to choose whether they want to participate in the program or not. Upon returning their vehicle, the company will let them know the total emissions released (based on the mileage) and how much it costs to offset them.7
There is no flat rate, ensuring that drivers pay only what they need to. For every ten kilometers (about six miles) driven, rental customers can support a Gold Standard Project at a rate of 0.2 SEK, or Swedish Krona (about USD0.023).7
These projects are excellent options for neutralizing your mileage, even if you occasionally drive a rental. Yet, you might not always rent from Enterprise, Hertz, or another company that provides offsetting opportunities. In this case, you’ll need to calculate the necessary offsets yourself, so you don’t get stuck with a rental car service that’s expensive and harmful to the environment.
Then, you can use a carbon offset company that provides real reductions of CO2, that not only mitigate the emissions from your rental, but also:
- Restores ecosystems to a balanced state
- Provides habitats for endangered animals
- Helps to filter the local water supply
- Gives benefits to the surrounding community
How to Calculate and Neutralize Your Rental Car Emissions
The best way to ensure your offset calculations are correct is to learn the total GHGs your rental car releases and the processes causing these emissions.
You don’t want to take emissions totals at face value, even when renting from companies like Enterprise and Hertz. You never know what they might exclude from the calculations, so you’ll want to double-check the totals yourself to verify that your emissions are indeed being offset, and not merely paying an extra price for the sake of greenwashing.
It’s best to start with a baseline of GHGs released per mile, which is about 404 g of CO2/mi for the average passenger car, and 5 tons of carbon dioxide per year. However, remember that this may change depending on the type of fuel you’re using. For instance, consider the difference between gasoline-fueled cars and diesel models:8
- Gasoline: 8,887 g CO2/gallon
- Diesel: 10,180 g CO2/gallon
Keep in mind that these emissions don’t just come from the combustion processes that run the engine, but conveniences that keep you comfortable while traveling. For instance, as mentioned earlier, HFCs leak from the vehicle when you’re using the air conditioning. Even small changes like choosing to roll down the windows instead of cranking up the A/C can dramatically change your rental car footprint.
Still, even electric vehicles aren’t entirely emissions-free, as their assembly and charging needs still rely on fossil fuels and destructive extraction processes.8
Plus, plug-in hybrid electric vehicles (PHEVs) still need gas, so they need electricity but can also still produce harmful tailpipe emissions.
Don’t get caught off-guard by all these caveats. The next time you’re planning on renting a car, refer to this overview, noting how cars differ in their emissions and where they come from.
Consider whether it would be wiser to use a gasoline- vs. diesel-powered vehicle in the context of your trip, and weigh that decision against how much CO2 you’re willing to emit and offset. While driving, pay attention to how you’re using the car (e.g., A/C vs. no A/C) to determine the best ways to minimize your rental’s environmental impact.
Stay Carbon-Neutral, Even When Renting a Car
You don’t have to compromise your carbon-neutral lifestyle to drive when you need to. Choosing to rent occasionally instead of buying, or traveling by rental car as opposed to flying, is a great way to cut down on your emissions and reduce your carbon footprint.
Still, rental cars emit GHGs, too, so you’ll need to be smart about how you offset them. Renting from a company that provides car rental carbon offsets is great, but it’s best to double-check that your emissions are truly being neutralized. Calculate your car emissions yourself after returning your next rental car to maintain your eco-friendly lifestyle.
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1US Environmental Protection Agency. (2021, July 27). Sources of greenhouse gas emissions. https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions
2International Energy Agency. (n.d.). Methane from oil & gas – Methane tracker 2020. https://www.iea.org/reports/methane-tracker-2020/methane-from-oil-gas
3Climate & Clean Air Coalition. (2014). Methane. https://www.ccacoalition.org/en/slcps/methane
4United States Environmental Protection Agency. (2021, July 27). Overview of greenhouse gases. Retrieved August 20, 2021, from https://www.epa.gov/ghgemissions/overview-greenhouse-gases#nitrous-oxide
5TerraPass. (2008). TerraPass is now on board with Enterprise Rent-A-Car. https://www.terrapass.com/blog/get-a-terrapass
6TerraPass. (2021, February 3). Enterprise, National, Alamo. Retrieved August 20, 2021, from https://terrapass.com/partner/enterprise
7Hertz. (n.d.). Hertz carbon offset program (Sweden): UN-approved climate compensation via Hertz Sweden. https://www.hertz.com/rentacar/productservice/index.jsp?targetPage=svSE_climate_compensate.jsp
8United States Environmental Protection Agency. (2021, July 21). Greenhouse gas emissions from a typical passenger vehicle. Retrieved August 20, 2021, from https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle