An improved automotive pump assembly includes a volute pumping chamber configured to operably contain a rotatable impeller which, when driven, draws fluid into a fluid inlet and pumps the fluid to and through a fluid outlet. The volute chamber has an exterior sidewall with a constant internal first radius over a first sidewall portion and transitions to a second sidewall portion of increasing radius. The chamber's second sidewall portion defines a first end at a sidewall transition point tangent to the constant radius sidewall segment to define a second end which is tangent to the volute chamber's fluid outlet with a second radius that is greater than the first radius.