The truck's low center of gravity makes for good handling and rollover prevention, and its technology makes jackknifing impossible, Musk said.
The semi has automated-driving features including lane-keeping and automatic braking, and has four independent motors, he said.
"Even if you have only two of the motors active, it'll still beat a diesel truck," he said.
On one charge, Tesla's truck can travel 500 miles at 60 mph, carrying the maximum allowed weight in the U.S., Musk said, adding that 80 percent of trucking routes are shorter than 250 miles.
Production begins in 2019, he said.
The prices of the truck and Roadster were not disclosed.
Market research firm Markets and Markets has estimated that the global market for traditional semi-trucks will hit $34.3 billion by 2020.
On Thursday, as Tesla was about to announce its electric semi, an advocacy group for diesel vehicle and engine manufacturers, diesel refiners and device makers issued a statement supporting the use of diesel-powered vehicles for trucking.
More than 4 million semi-trucks travel America's roads, with more than 98 percent of them diesel powered, the Diesel Technology Forum said.
"Diesel is the most energy efficient internal combustion engine," said Allen Schaeffer, the group's executive director.