speed up

verb

1. To accelerate; to increase speed.

   “The car sped up as it went around the corner.”

2. To accelerate (something): to increase its speed, to make it go faster.

   “You shouldn't speed up your car when you go around corners.”

   “More fast trains between England and Scotland, and additional "car-sleeper" overnight services for motorists, are important features of British Railways summer timetables, which come into operation on June 17. In all, 98 long-distance trains will be speeded-up to save 10-75 min. and many will make non-stop runs at an average speed of 60 m.p.h. or more.”