Not necessarily, it can mean disabling aircon, driving the lower speed limit, taking a flatter route, etc

It’s not always about quality or performance, you want cars to be comfortable too, which is why you have to make tradeoffs. One thing hypermilers sometimes do is taping the seams on the hood, door, etc to improve aerodynamics. You could make a car from factory without seams in the body, but you won’t sell very many unless you can convince people to crawl in through a window.

Other things may be prohibitively expensive, or not durable, so you make tradeoffs. As efficient as possible while staying within the chosen price class and providing a certain standard of comfort.