The 2014 Chevrolet Impala, a completely reworked version of the full-size car, has taken Consumer Reports magazine's top spot for all sedans.

DETROIT — The Chevrolet Impala, long the standard-bearer for mediocre cars, has made an amazing turnaround.

A completely reworked version of the full-size car has taken Consumer Reports magazine’s top spot for all sedans, deposing German and Japanese cars for the first time in at least 20 years.

The new version, which began arriving in showrooms in April, scored 95 out of 100 points in the magazine’s testing to get an “Excellent” rating. Only two cars have earned higher scores, the electric Tesla Model S, which starts at $62,400, and the BMW 135i coupe with a base price of $39,300.

The performance of the 2014 Impala, which starts at just under $27,000, is a sign of the three Detroit automakers’ renaissance, said Jake Fisher, the magazine’s chief auto tester. All three companies nearly collapsed into financial ruin just four years ago, partly because of their reputation for shoddiness.

“We’ve seen a number of redesigned American models — including the Chrysler 300, Ford Escape and Fusion, and Jeep Grand Cherokee — deliver world-class performance in our tests,” said Jake Fisher, the magazine’s auto testing director.

The Impala, made by General Motors, surprised the magazine’s auto testers with its ride, agility, braking, high-quality materials and quiet, roomy cabin, Fisher said. Its score was 32 points higher than the previous model, a noisy sedan with uncertain handling that mainly was sent to rental car lots.