upshift

up·shift

U0137300 (ŭp′shĭft′)intr.v. up·shift·ed, up·shift·ing, up·shifts To shift a motor vehicle into a higher gear.
up′shift′ n.

upshift

(ʌpˈʃɪft) vb (tr) (of vehicles) to move up a gear

up•shift

(ˈʌpˌʃɪft)
v.t. to shift (an automotive transmission or vehicle) into a higher gear. [1950–55]