[jakeru]

I'm not sure high pushing effort is necessarily a "problem", as cars are generally designed to be moved under engine power and not pushed, but presuming your car is getting good fuel economy/ gas mileage, or if such "easy pushing performance" is an important factor to you for how you use the car (sounds like it is), I'd suggest that tire pressures could play a huge part in the effort (with increased tire pressure giving lower rolling resistance, probably noticeable when "pushing" the car) and aside from that, tire design could also be a significant factor. (With many newer and increasingly popular "low rolling" resistance tire designs potentially having noticeable difference in pushing effort compared to other styles which compromise other tire performance factors, such as increased cornering grip, reduced tire weight, and so on.