How EVs, Gasoline and Hybrid Cars Actually Work

Three propulsion systems now compete for buyers worldwide: conventional gasoline engines, hybrid-electric vehicles (HEVs), and all-electric vehicles (EVs), with plug-in hybrids (PHEVs) sitting in between. Each converts stored energy into motion through a different mechanical and electrical path, which affects driving range, refueling or recharging time, and tailpipe emissions.

How a gasoline car moves

A conventional gasoline vehicle burns fuel inside an internal combustion engine, which turns a transmission and then the wheels. According to the U.S. Department of Energy's FuelEconomy.gov, gasoline vehicles convert only about 12% to 30% of the energy stored in the fuel into power that actually reaches the wheels; most of the rest is lost as heat during combustion.

How an electric vehicle moves

The U.S. Environmental Protection Agency (EPA) describes an EV as having "a battery instead of a gasoline tank, and an electric motor instead of an internal combustion engine." FuelEconomy.gov adds that EVs are propelled by one or more electric motors powered by rechargeable battery packs, which are recharged by plugging into an electric power source and through regenerative braking while driving.

That design converts stored energy into motion far more efficiently. FuelEconomy.gov states that EVs convert over 77% of the electrical energy drawn from the grid into power at the wheels, compared with the 12%-30% figure for gasoline engines.

How hybrids and plug-in hybrids combine both

A hybrid electric vehicle (HEV) pairs a gasoline engine with an electric motor and a battery, but the battery cannot be plugged in. Per the Department of Energy's FuelEconomy.gov, the battery is charged only through regenerative braking and by the combustion engine itself. The electric motor assists the engine during acceleration, passing or hill climbing, which lets manufacturers use a smaller, more efficient engine, and the engine automatically shuts off at stops to avoid idling.

A plug-in hybrid electric vehicle (PHEV) combines a battery, an electric motor, a gasoline tank and a combustion engine, and it uses both electricity and gasoline as fuel sources, according to the EPA. Unlike a conventional hybrid, a PHEV's battery can also be recharged from an external power source. The EPA states that PHEVs produce tailpipe emissions whenever the gasoline engine is running.

Regenerative braking, explained

Regenerative braking is a feature shared by EVs, HEVs and PHEVs. FuelEconomy.gov describes it as a system that uses the forward motion of the wheels during coasting or braking to turn the electric motor in reverse, which both slows the car and sends electricity back into the battery, recovering energy that a conventional gasoline car would lose entirely as heat in its brakes.

Measuring emissions

The EPA states that EVs produce zero tailpipe emissions, while charging the battery may add some pollution at the power plant depending on how the electricity is generated. Even so, the EPA says total emissions linked to driving an EV are typically lower than for a gasoline car, particularly where electricity comes from renewable sources such as wind. PHEVs produce tailpipe emissions only when their gasoline engine is running, while conventional HEVs and gasoline cars emit pollutants from the engine continuously during operation.

Why this is getting attention now

The question of how these systems differ is becoming more relevant as EV sales rise globally. The International Energy Agency's Global EV Outlook 2026 found that electric car sales grew 20% worldwide in 2025 to exceed 20 million units, meaning about one-quarter of all new cars sold that year were electric. The IEA projects sales will reach 23 million in 2026, close to 28% of the global total.

Regional adoption varies sharply, the IEA reports. In China, electric cars accounted for nearly 55% of all car sales in 2025. In Europe, sales rose more than 30% to reach 28% of the market, which the IEA links to tighter European Union CO2 standards for cars. In the United States, electric car sales stayed just under 10% of the market, and the IEA says the end of federal EV tax credits coincided with a drop in sales toward the end of 2025.

The IEA also estimated that the global EV fleet avoided the consumption of around 1.7 million barrels of oil per day in 2025, a figure the agency projects could triple to about 5 million barrels per day by 2030.

Trade-offs that remain

FuelEconomy.gov notes that gasoline vehicles still offer longer driving range on a single fill-up and faster refueling than EVs, which can take between roughly 3 and 12 hours to fully recharge depending on the charger used; FuelEconomy.gov notes a fast charge to 80% capacity can take around 30 minutes on chargers built for that purpose. Hybrids and plug-in hybrids are positioned as a middle option: HEVs need no charging infrastructure at all, while PHEVs can run short trips on electricity but still rely on gasoline for longer journeys, per the EPA.