a lot will depend on the car too, I think the fuel injected ones are more efficient than the carburetor fuel systems of the past.
Maybe that saying came about back in the carburetor days.


How you drive , how much farther the distance, stops & starts /city vs highway.. all plays a part.

short trips are harder on the engine if it doesn't get warmed up enough - oil takes a while to warm up to best operation temps - for engine protection.
If you usually only take short trips let the engine idle a few minutes before you get going. Especially if you have to go uphill or accelerate quickly right away.