Final answer:
The question pertains to the legal and safe maximum driving speeds for passenger vehicles on roadways, factoring in the efficiency of speed related to air drag and energy consumption. Historically, during the 1970s oil crisis, speed limits in the U.S. were set to about 90 km/h (55 mi/h) for maximum fuel efficiency.
Step-by-step explanation:
The question posed concerns the maximum speeds at which a passenger vehicle may legally and safely travel. When talking about non-ideal conditions, such as those on a public roadway, the prudent maximum speed would be the one that aligns with posted speed limits and traffic regulations, which typically take into account a variety of contributing factors like vehicle handling at different speeds, road design, weather conditions, and overall road safety.
During the 1970s oil crisis in the United States, highway speed limits were reduced to about 90 km/h (55 mi/h) in an effort to conserve fuel. This was partly because at highway speeds, a considerable amount of a car's power is expended on overcoming air drag, and it was found that the most fuel-efficient speeds were around 70-80 km/h (45-50 mi/h). Nevertheless, the discussion of ideal speed pertains to the physics concept of a car's ability to take a turn on a curve without relying on tire-to-road friction. This ideal speed is much lower than the record land speed mentioned in the discussion, emphasizing the difference between theoretical physics scenarios and practical driving circumstances.