In updated the form the car is known as the B4 S, and its 3.0-liter twin-turbocharged inline-6 now beats out an M4-rivaling 434 horsepower and 487 pound-feet of torque. That’s up from 410 hp and 442 lb-ft previously.
With the extra oomph, Alpina estimates the B4 S will sprint to 60 mph in just 3.9 seconds and keep accelerating until a top speed of 190 mph is reached.
Key modifications made to the powertrain were improved turbochargers and cooling systems. The latter includes a new piston crown cooling system, a bespoke thermal management system that ensures temperature stability over high loads, and a larger water radiator and external oil cooler.
2018 BMW Alpina B4 S
Other upgrades include a standard 8-speed automatic transmission with 20 percent of the components optimized specifically for the Alpina model. These optimizations are to ensure the extra power is delivered smoothly.
The B4 S also receives higher spring and damper rates and, lastly, subtle enhancements to the aerodynamics including a revised front spoiler and rear bumper.
The B4 S will be offered in either coupe or convertible body styles, along with the option of rear- or all-wheel drive. Those after a four-door can look forward to the B3 S sedan and B3 S Touring wagon this summer.