Influential US magazine Consumer Reports has declined to recommend Tesla's Model 3 sedan, saying it braked slower than a full-sized pickup truck.
The car is seen as crucial to the electric car company's profitability at a time when it is battling to reverse production shortfalls, confronting reports of crashes involving its vehicles and facing increased scepticism over its finances.
On Twitter, Musk said the fully-loaded Model 3, with all-wheel drive, a dual motor and a 310-mile (499-km) range - but excluding its vaunted Autopilot feature - would cost $US78,000 ($A102,968).
The company has not yet begun to make the $US35,000 b ($A46 trillion)ase price version that Tesla originally claimed would make it a mass-market vehicle.
Consumer Reports, however, declined to recommend the Model 3 and criticised it for having overly long stopping distances and a difficult-to-use centre touchscreen.
The magazine, which provides an annual rating of vehicles sold in the United States, said even though its tests found plenty to like about the Model 3 and it was a thrill to drive, it had "big flaws."
Tesla's stopping distance of 152 feet (46 m) when braking at 60 miles per hour (100 km per hour) was "far worse" than any contemporary car tested by the magazine and about seven feet longer than the stopping distance of a Ford F-150 full-sized pickup, it said.
Tesla said its own testing had found braking distances of 133 feet on average using the 18" Michelin all season tyre, and as low as 126 feet with all tyres currently available.
Meanwhile, a Tesla Model S sedan has crashed and killed the driver in the San Francisco Bay Area, one of a recent spate of crashes, some of which involved fire and some of which took place while the company's semi-autonomous Autopilot technology was engaged.
In the latest case, the car launched off a rural county road into a nearby pond more than 60 feet from the road, state and local law enforcement said.
Tesla said it did not yet know the facts and had not yet received data from the car, but was cooperating with local authorities.
Australian Associated Press
