Simple past tense and past participle of upshift.(verb)
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Use "upshifted" in a sentence
"I used the paddles on the steering wheel and upshifted, letting the car have its way, coaxing it to higher and higher speeds."
"It was cloudy, but still muggy, and the sweat drenched her bike shorts and T-shirt as she upshifted into high gear and began to do some serious cranking on the pedals."
"She laughed, plugged the earpiece in and upshifted."