Performance cars come in many shapes and sizes. There are lightweight roadsters, hypercars, and even crossovers. Some of these are more subtle than others. After all, some want to show the world how much power they have under the hood. But some want to keep things a little more restrained.

With that, you can put the 2021 Alpine B8 Gran Coupe under the Sleeper category.

From the outside, it looks like a standard 8 Series Gran Coupe. It doesn't even have the aggressive bumpers and bulging fenders of the M8 Gran Coupe. The only clues you have are the multi-spoke wheels (an Alpina signature), Alpina spelled out on the front apron, and four exhaust pipes.

Inside, you won't see the usual performance car cues plastered all over the place. There are no red stitches, carbon fiber trimmings, or even thin bucket seats. If anything, it's the exact opposite of what you expect in a performance car. In the B8 Gran Coupe, you have brown leather, wood panels, four individual seats, and even a crystal gear selector.

The subtle exterior and the plush interior are good disguises for what lurks under the B8 Gran Coupe's lengthy hood. It uses the same 4.4-liter, twin-turbo V8 from the M850i xDrive. However, it gets 90 PS and 50 Nm of torque more from the standard engine. The result is 620 PS and 800 Nm of torque, a substantial increase from the stock model's 530 PS and 750 Nm figure.

How fast is this Alpine four-door coupe? According to factory figures, the B8 Gran Coupe can do the 0 to 100 km/h sprint in just 3.4 seconds. It's a shade slower than its BMW-badged sibling, the M8 Gran Coupe Competition. That one does the same task in a mere 3.2 seconds. However, the B8 Gran Coupe isn't governed by speed limiters, giving it a top speed of 324 km/h. With figures like that, this discreet executive express is also one of the fastest four-doors out there.