The first passenger-carrying tilting trains on the main West Coast line between London and Manchester begins on Monday morning, Virgin Trains says.
The tilting mechanism should cut journey times by 35 minutes
The firm says the total journey time between the capital and Manchester will be cut by an average of 35 minutes.
The first service was due to leave London Euston at 0952 BST and arrive at Manchester Piccadilly at 1244 BST.
The Pendolinos have been used on half of the timetable but the tilting mechanism had been out of use.
Drivers will now gain experience before the service is speeded up to 125mph in September 2004.
The new technology allows trains to travel around bends at higher speeds.