Singer has returned with a wild upgrade for the 964-generation Porsche 911 that turns it into something resembling Porsche's 934/5 race car that dominated the Trans Am Series in 1977. There's also power to back up the wild looks as Singer has tuned the 911's flat-6 engine to deliver more than 700 hp.

After launching a Mustang GT3 race car earlier this month, Ford has followed up with a Mustang GT4. The latest race car is aimed exclusively at customer teams and is closely related to the new Mustang Dark Horse that will be in showrooms later this summer.

Mercedes-Benz AMG's S 63 E Performance is on the way, and while there's still a V-8 under the hood the engine is now augmented by a sophisticated plug-in hybrid system that uses technology similar to that found in Formula 1. Peak output is 791 hp, and we just put it to the test.

You'll find these stories and more in today's car news, right here at Motor Authority.

Singer channels the Porsche 934/5 for its latest custom 911

Seventh-generation Ford Mustang spawns GT4 race car

Review: 2024 Mercedes-Benz AMG S 63 E Performance civilizes big horsepower

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