Not necessarily so. Spend the extra money on weight savings and friction loss. Honda civic beats 40 mpg. Spend an extra 5k on skinny tires gear changes less steel and corresponding lighter brakes this and that and it could get past 50 easily.
Then it would be a cheap assed car like a. Prius but dooable
40mpg in stop and go traffic? This is where the hybrid shines. The engine may never turn on and it is all battery if the speed is less than 30mph. No jack rabbit starts accelerate discharge the battery coast and break to a stop charge the battery.