Sentence:  Having put the engineer at ease, I think, it was time to <WSD>give</WSD> the car <WSD>some welly</WSD> and I was amazed how effortlessly it rocketed up to, er, high speeds, then lost speed almost as rapidly when the powerful brakes came into use. 
Meaning of the word marked with <WSD> tags:  To increase fuel or power to an engine, as to a car by depressing the gas pedal.