The Rolls-Royce Phantom’s top speed is 155 miles per hour.
That figure applies to the current Phantom VIII, introduced in 2017 and still in production. Its 6.75-liter twin-turbocharged V12 produces 420 kW and 900 Nm of torque, sending power through an eight-speed automatic transmission. Rolls-Royce prioritizes quiet, effortless progress over sports-car acceleration, but the Phantom is nevertheless capable of reaching its electronically limited 250 km/h—about 155 mph—top speed.
The Phantom name dates to 1925 and has been used across eight generations, so specifications can vary depending on which version is meant. That is the main source of confusion in this question: early Phantoms were much slower, while related modern models such as the Phantom Coupé also used a 155-mph limit. The current saloon’s quoted performance is about 5.3 seconds from 0 to 100 km/h, remarkable for a hand-built luxury car weighing more than 2.5 tonnes.