Less density does not automatically translate to longer commutes or more car use.

Some of the least dense areas are farmland. Where there are mostly family farms the commuting distance is zero since folks live and work in the same place. Likewise northern Alaska has very low density, but with small villages the commutes are also short to none.

The key isn't density, but the average distance between residence and work. Here in the USA we tend to zone so there are industrial/commercial areas with little or no population and bedroom communities with little or no commerce, often not even retail.

Compare to Italy for example where you'll see a mix of factories, farms, residences, and shops within limited areas, so people have plenty of job opportunities close to home.

Some years back I had the opportunity to visit a component maker outside of Taichung. It was a semi-rural/small town area and I was very surprised to see only 1 bicycle parked in the rack out front. I commented about the lack of bike use among the workers of a bicycle component maker to the manager, and asked if perhaps the workers left their bikes out back. Answer --- Oh, no. Very few workers rode to work, they tive too close and walk instead.

This pattern was common throughout Taiwan, where businesses on the outskirts of the cities hired locally and workers opted to walk to work.