When electric and hybrid vehicles first came on the market, they were prohibitively expensive for many consumers. That's no longer the case.

More modestly priced low-emissions vehicles have since been introduced, and new research suggests the greenest cars are some of the cheapest options when operation and maintenance costs are considered.

"If you look in aggregate at the most popular vehicles on the market today, one doesn't have to pay more for a lower carbon-emitting vehicle," Jessika Trancik, a professor of energy studies at MIT's Institute for Data, Systems, and Society, told MIT News. "In fact, the group of vehicles at the lower end of costs are also at the lowest end of emissions, even across a diverse set of alternative and conventional engines."

Trancik and her colleagues recently tallied cost and emissions estimates of a 125 U.S. auto models. The cost of each car was calculated on a per-mile basis, accounting for both sticker price and maintenance costs over the lifetime of the vehicle. Emissions estimates included both greenhouse gas emissions during operation and those emitted during the production process.

"To enable a fair comparison between cars of all technologies, we include all emissions coming from the fuel, electricity, and vehicle production supply chains," said Marco Miotti, a doctoral student at IDSS.

Their analysis shows smaller electric and hybrid vehicles like the Toyota Prius are some of the least expensive vehicles to own and operate on a per-mile basis.

"Our results show that popular alternative-technology cars such as the Nissan Leaf can already save a considerable amount of emissions today, while being quite affordable when operating costs are considered," Miotti observes. "Notably, the benefit of the efficient electric powertrain far outweighs the added emissions of manufacturing a battery."

In addition to publishing their analysis in the journal Environmental Science and Technology, the scientists incorporated their findings into a new mobile app aimed at helping consumers make better economic and environmental car-buying decisions.

"There are a lot of opportunities for decarbonization in the transportation sector," Trancik said. "It's fairly easy to buy a lower-emissions vehicle if you have easy access to this information."

The transportation sector accounts for roughly 28 percent of greenhouse gas emissions in the United States, and cars, buses and smaller trucks are responsible for about 60 percent of those emissions. Researchers say more U.S. consumers need to adopt low-emissions vehicles if catastrophic climate change is to be avoided.

"To meet mid-century climate policy targets, what we would likely need to see is a near-complete electrification of vehicles within a few decades, alongside a decarbonization of electricity," Trancik concluded.

One way to make sure that happens, researchers say, is to give consumers the most accurate information.