The car has come a long way since Henry Ford's Model T.
Today's vehicles are fast, stylish and increasingly fueled in environmentally friendly ways.
In this slideshow, CNBC's "Sustainable Energy " takes a look at some of the innovative ways that modern autos are fueled.
—By Anmar Frangoul, special to CNBC.com, on Friday August 7, 2015.
London's red double-decker buses are famous the world over, but now, single-deckers fueled by hydrogen are helping cut pollution in the city.
A fleet of eight hydrogen fuel cell buses run between Covent Garden, in the heart of London's theater district, and Tower Gateway in the east of the city.
Their only emission? Water.
Earlier this year, Mayor of London Boris Johnson said there were plans to add two extra hydrogen fuel cell buses to the RV1 bus route.
This will enable the route to operate as a "complete zero-emission route," he said.
In January 2014, Ford unveiled plans for a new solar-powered hybrid car.
The Ford C-MAX Solar Energi Concept will harness the sun's power with a "special concentrator" that will act like a magnifying glass, "directing intense rays to solar panels on the vehicle roof."
Ford isn't the only team to develop a solar-powered car. A team of students at the Netherlands' Eindhoven University of Technology have developed Stella Lux, a solar-powered family car that they say generates more power than it consumes.
According to the its creators, the Stella Lux can travel up to 1,000 kilometers (622 miles) on a sunny day.
Headlines were made in 2010, when GENeco—a subsidiary of British utilities company Wessex Water—conducted a trial of the Bio-Bug.
Shaped like a Volkswagen Beetle, the Bio-Bug was powered by human waste from a sewage treatment works in Bristol, England.
Inspired? According to GENeco, the waste flushed down the toilets of 70 households would produce enough biomethane to power the Bio-Bug for a whole year.
In 2011, the wind-powered Wind Explorer car completed a 5,000 kilometer trip traversing Australia.
The vehicle was powered by lithium-ion batteries that were charged by a mobile wind turbine when conditions permitted.
Evonik Industries, the German company that provided the battery and shell of the vehicle, said that the Wind Explorer managed a stretch of 493.5 kilometers using nothing but wind power—the longest ever managed.
The car weighed only 200 kilograms (441 pounds) and ran up an electricity bill of just 10 euros ($11) across the 5,000 kilometers, according to Evonik.
NanoFlowcell has developed a flow cell battery system that can power an automobile—for the first-time ever, the Liechtenstein-based company says.
The company's compact flow cell battery is charged using ionic liquids, which are pumped through battery cells containing electrodes.
It may seem unlikely, but electric cars are nothing new. The first electric vehicles date back to the late 1820s, according to the U.S. Department of Energy.
Today, of course, electricity-fueled cars are some of the most advanced autos out there—and environmentally friendly too.
Tesla's Model S, for instance, is a zero-emission vehicle, with autopilot features including automatic emergency braking and blind spot warning. It can travel up to 330 miles without being charged and go from 0 to 60 mph in 2.8 seconds.
The potential of electric vehicles is huge. The U.S. Department of Energy says that if hybrid or electric vehicles completely replaced light-duty conventional ones, U.S. dependence on foreign oil would fall by 30-60 percent. Plus, carbon pollution from the transport sector would fall by up to 20 percent.
Ethanol is a renewable fuel made from biomass—plant materials—that can be used to run cars.
Swedish car maker Koenigsegg released the bio-fueled CCXR in 2007. The "green" supercar can run on either normal gasoline or pure ethanol, or a combination of the two.
As consumers become more eco-conscious, hybrid cars that have both an electric motor and a petrol engine are gaining in popularity.
Launched in 1997, the Toyota Prius (pictured) was the world's first mass-produced hybrid and provides a "genuine alternative to petrol and diesel engines," according to the Japanese car manufacturer.
Today, drivers are spoiled for choice. Vauxhall's Ampera, for instance, is a hybrid that costs around a quarter of the price to run of a petrol-powered car and is cleaner in terms of emissions, according to the British company.