At a demonstration at the Tesla Motors Inc. (NASDAQ:TSLA) design studio in Hawthorne, Calif., Tuesday night, Tesla CEO Elon Musk attempted to dispel doubts that electric cars will never be as convenient as traditional gas-guzzlers. Musk unveiled a battery-swap system that will give a Tesla Model S a complete charge in just 90 seconds.

That battery-swap demonstration took place on stage while a video showed a Tesla employee filling a gas tank. Musk assured the crowd that Tesla searched for the gas station in Los Angeles with the fastest fill-rate (10 gallons per minute) and told the demonstrator to fill the tank as fast as he could.

Fast Pack Swap Event from Tesla Motors on Vimeo.

It took more than four minutes to fill the 23-gallon gas tank, which gave Musk time to demonstrate the Model S battery-swap service twice, with time left over to crack jokes about how he was boring the audience. The new battery-swap service is certainly an upgrade from the 20 minutes to an hour it takes to charge a Model S using the current Tesla “supercharging” stations.

The battery-swap service stations will be added to the network of supercharging stations Tesla is building around the nation. The supercharging will remain free, but the 90-second battery swap will cost between $50 and $80. Tesla has been investing heavily in building supercharging stations and said it will have more than 100 locations by the end of the year, allowing drivers to drive a Tesla car from Los Angeles to New York.

“The only decision you need to make when you come to one of our Tesla stations is: Do you prefer faster or free?” Musk said at the demonstration.

Despite the announcement of the battery-swap service, Tesla’s stock fell about three points on Friday morning.  

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