A faint hum replaces what is normally the sound of a pump, gas and exhaust in a car.

The classic American muscle car is not broken. It's powered by electricity.

There is a small but expanding group of tinkerers, racers, engineers and entrepreneurs across the country who are converting vintage cars and trucks into green and fast electric vehicles.

As battery technology improves and the world looks toward cleaner energy to combat climate change, electric car conversions are becoming more mainstream.

RC cars are fast, so that's kind of a compliment to me. Public charging stations are becoming more and more common across the country.

The cargo pilot bought the car for $6,500 at the end of the year. He embarked on a year-and-a-half-long project to convert the car into an electric vehicle, using battery packs, a motor and the entire rear sub frame from the crashed Model S.

"This was my way of taking the car that I like, and then taking the modern technology and performance, and mixing them together."

According to Jonathan Klinger, vice president of car culture for Hagerty, an insurance company and automotive lifestyle brand that specializes in collector vehicles, converting classic cars into EV's is definitely a trend.

The company conducted a survey in May of about 25,000 automobile enthusiasts in the United States, Canada and the United Kingdom. About 1% of people have converted their classic to run on an electric vehicle.

The respondents' top three reasons for converting their vehicles were for faster acceleration, improved performance, and a fun and challenging project. Some respondents said they approve of classic vehicles being converted to electric vehicles.

"Electric vehicles deliver some pretty astonishing performance just by the nature of the mechanics of how they work." He's not surprised that a small percentage of classic car owners want to improve their performance. The hot-rod movement of the 1950s was compared by him.

He doesn't think electric motors will replace internal combustion engines in historically significant vehicles.

He said that having a vintage car that has a carburetor is the same as having a new one. Some people want to keep the sound and rumble of older cars.

The time it takes to realize a positive environmental impact is one of the barriers to converting cars. It takes more time to offset the initial carbon footprint of manufacturing the batteries because classic vehicles are driven for less than 1,500 miles a year.

There is the price.

A car that was destined for the landfill was modified by a co-owner of the business. The year-and-a-half-long project cost more than $100,000 and revealed several other obstacles.

The group replaced the underpowered gas engine with a motor from a crashed Model S and installed 16 batteries.

The increased performance that comes with an electric motor is not something that most classic vehicles were designed to handle. The car's suspension, steering, driveshaft, and brakes had to be beefed up.

The result is a vehicle that has a Ford F-150 pickup and a Dodge Durango SUV as well as disc brakes and coil-over shocks in the front and rear.

It's still not realistic for a casual car tinkerer to have the resources to do such a complicated project as Ford and GM have done. He believes it will take a while for EV conversions to become mainstream.

He thought it would be 20 years. It will take 20 years before most of the cars at a car show are electric.

Mike Spagnola, president and CEO of the Specialty Equipment Market Association, said that reality could be coming sooner than anticipated.

In Las Vegas this fall, some 21,000 square feet of convention space was devoted to electric vehicles and their parts. There was only 2,500 square feet of space at the show.

Universal parts, lighter, smaller and more powerful battery packs are being developed by companies. They're making wiring components that are simpler to install. The frames are being built with the electric motor, batteries and components already installed The classic vehicle's body can be put on the platform by buyers.

Spagnola said that the early adopters of this would take a crashedTesla and pull the motor and harnesses and batteries and all that out of the vehicle and build a new vehicle. Many manufacturers are now making components. We're really looking forward to it.