Why can't a person lie down in a car with a width of 1.8m?
3 Answers
After deducting the width of the two side mirrors and the body structure on both sides from the 1.8m car width, the actual interior width may only be around 1.6m, making it impossible to stretch out fully when lying down. Concept: Car width refers to the distance between two parallel planes that are parallel to the vehicle's longitudinal center plane and touch the outermost fixed protrusions on both sides of the vehicle (excluding side mirrors, side marker lights, turn signals, flexible mudguards, and tire deformation where they contact the ground). Regional regulations on car width: Width mainly affects passenger space and maneuverability. For passenger cars, if three seats need to be arranged side by side with sufficient width, the car width generally needs to reach 1.8m. The Japanese government imposes stricter limits on car width, with most vehicles under 1.8m, while European cars tend to have wider bodies. However, an overly wide body reduces convenience for urban driving and parking, so for passenger cars, 2m is widely recognized as the upper limit. Vehicles approaching or exceeding 2m in width become difficult to drive. For vehicles with non-folding side mirrors, the listed width in specifications usually includes the extended mirrors, which is why some European passenger cars have listed widths approaching or exceeding 2 meters. Even after removing the width of two side mirrors and the body structure on both sides, the interior width is still less than 1.7m, making it impossible to stretch out fully when lying down.
I've driven quite a few cars, and while a 1.8-meter width may sound spacious, it's completely inadequate for lying down. The main reason is that the car width refers to the external body dimensions, including door thickness and bumpers. The actual interior width is usually around 1.5 meters, and you have to subtract space taken up by the dashboard, center console, and other features, leaving no flat area. A person needs at least 1.8 meters of uninterrupted space to lie down, but car seats are tilted and there are airbag designs, making it easy to hit your head or waist, which affects driving safety. On long trips, some people think they can rest by lying in the back seat, but the rear is even narrower—you can only curl up at most, with no room to stretch your legs. I recommend stopping at a service area or using a folding chair for proper rest.
From an automotive design perspective, a vehicle width of 1.8 meters is merely an external measurement. The interior space is significantly compressed, with the actual usable width being less than 1.4 meters due to the additional thickness occupied by the body panels and interior materials. The cabin is also filled with various control devices, such as the dashboard protruding in the middle, making it impossible to lie down without encountering these obstacles. More importantly, vehicle design prioritizes seating posture, with all component layouts ensuring the driver sits upright rather than lying flat to mitigate accident risks. I've examined the layout of certain models; some compact cars have rear seat widths of only about 1.2 meters. The space is inherently limited, and forcing oneself to lie down could potentially trigger electrical faults, posing significant safety hazards.
