Distance judging is critical in driving. Human judge distance by either seteroscopic vision or by visual cue. Stereoscopic depth perception is only good to about 20 ft. After that, eyes use visual cues for depth perception. Mainly you compare size of an object with nearby object to figure out how far something is. A tree, sign post or another car is used to compare size and distance.
For normal driving visual cue is used for depth perception for 99% of the time. Visual cue depth perception need to see the big picture. Large windows are necessary to see the big picture to judge distance between you and another car. Large all around visibililty is critical for driving safety.
Lane change require driver to take eyes off front of road to see behind them for a split second. Within that time, driver need to tell whether car in next lane is approaching quickly or same speed. Drivers need to see the entire view behind the car for visual cue to quickly judge distance and approaching speed of traffic.
Cars windows began to get smaller starting around 2000. Prior to that window size reached the largest in the 80's especially on Honda which were know for their greenhouse style glass as well as BMW and many other brands.
The BMW cars use to have great visibility. Large windows and thin pillars. The 6 series in particular had thin body and large bay windows you. It was displayed at NY Museum of Modern Art as an example of good design.
Honda's mantra was people large machine small. They had low beltline, and large windows. That was what made Honda popular. People liked the way they felt.
Of the 80's cars, the Nissan Stanza had the biggest windows with minimal pillars. This is of a little more visibility than necessary.
After 9/11, the American psych changed. People wanted security. Bigger and larger houses were popular.That translated into their transportation as well. Hummer started the trend towards small gun slit windows. It had all the elements for post 9/11. After all, it's bigger brother, the original H1 was the vehicle that helped win the triumphant Iraq War I. The H1 was all over TV. It was a symbol of American might. If any vehicle made people feel safe, it was the Hummer. GM bought the Hummer brand and came out with Hummer H2 in 2003. Build on a truck chassis. It had high beltline and small windows. The style was that of the original H1. A key feature was the gun slit small windows. It was reminiscence of an armored carrier. The door even looked like it was armored. Large house and an armored vehicle was the security blanket for the American public. Sales of H2 immediately took off. That was the start of the trend to small gun slit windows.
Toyota bought out the FJ Cruiser in 2006. People were shocked by how ugly it was. High beltline and small windows. Then there was the highly offensive C pillar that blocked whatever view there was to the rear. But that car sold well. Is still essentially the same 10 years latter with the same body style. Jonathan Ward at ICON4X4 was originally asked by Mr. Toyoda to build prototype for the FJ cruisers. They build 3 prototype that was close to the original FJ Cruiser. However, Toyota decided to go with new FJ style with hidious visibility and small window.
Original FJ Cruiser
New FJ Cruiser
Trend continuted with 2010 Camero along with many other cars that spot smaller and smaller windows.
Frequent question is whether small windows were necessar for side impace protection required by NHTSA. There is nothing physically impossible about making a safe car with large windows. Especially with side airbags. Doors can be made thicker if necessary to house reinforcement. Airbag can be used to protech occupants against window. The reinforcement beam inside the door is actually at bumper level that is very low. The door latch is also low in the door. The key load path is the beam and the door latch. Everything above that is just sheet metal. If high beltline were necessary, then why do new cars like Hyundai Elantra have larger driver window, but small passenger window. Look at the size if the driver window. The front extends down almost to to top of the wheel. The rear you can't see out of. If high beltline was for safety, then is the safety only for the rear passenger and not the front.
Small windows is really for style.
Can mirror and camera compensate for poor rear visibility. The answer is yes to some extent. Cameras have a distorted view to the rear. Judging distance will be compromised, and take some time to adjust. Side sensor may help, but are they good enough to judge speed of approaching cars or are they just a dumb sensor.
Lastly, sitting inside a car with high beltline is simply boring. People love convertable because they are open. Feel the sun and wind. My old 87 Chevy Sprint in college had great visibility. It was dog slow, but I get a smile everytime I get into it. In contrast, in our VW Passat rental we had for a week long vacation, I was dreading getting into that claustrophobic poor visility machine. True, it looks cool outside, but few hours inside, and I want out. My daughter hates it because she can only see half the view outside. She complained incessantly during the entire holiday about getting into the car. In contrast, she loves my old 85 4Runner because the window extends almost down to her chest, and she get the full view outside. Both kids end up playing video games until the got bored and complained. In case you wonder, they actually love car trips. We drove our family car half way thru the US the previous year, and they loved it. Just not in the VW Passat. Yes, small windows really are that bad for kids.
Interestingly car companies are worried that young people are not excited by cars anymore. I do wonder if my observation of kids have anything to do with it. My kids hated the rental VW Passat because it is so boring to stare at the interior for hours. If that was our full time family car, I can see that they would grow up hating cars. Adults may like the fake leather interior because of its "quality" look. Kids really don't care to stare at the "high quality" fake leather for hours on the trip to see grandparents. Even for me, driving that VW Passat was boring and a choir. It was the worse part of the trip. Like sitting in a jail for hours.
Many analyst thinks Subaru and Mazda will go the way of Saab, Isuzu, Suzuki and other small car companies in the US. Subaru has made cars that makes sense with safety, economy, visibility in mind regardless of current styling trend. Subaru has boldly kept their large window size. Subaru has always been know to be strong in a roll over crash despite their large windows and thin pillars. Racers has know that. On youtube, a WRX did a high speed multiple roll with the roof fully intact. In another car the roof would have been completely crushed. Other manufactures said they cannot make a strong roof with thin pillars. Subaru did it. On a second note, for their 4th generation Impreza, the reduced the engine size from 2.5l to 2.0l back in 2011, decreasing hp from 170hp to 148hp. Gas mileage went from 20-27mpg to 25-34mpg. Mileage was nheard of at the time for an AWD. They were the first manufacture to actually reduce engine power for fuel economy. Remember this was the time when bigger was better. So what was the result of Subaru building a car that makes sense. Obviously enough of the public noticed. They have just set their 5th consecutive yearly sales record. Their problem now is they can't keep up with demands.
Subaru did reduce the size of the window on the 2011+ Impreza, and there was an outcry from their loyal customer base. Is barely ok now, but not horrible like many other cars. Their Legacy and Outback line still have relatively large windows. There is hope that Subaru's record will get other manufacture's attention and go back towards a sensible car design with proper visibility.
Scion is the Toyota brand that tries to attract young people to the Toyota fold. The intent was to sell low cost cars that only appeal to young people and get them on board with Toyota. Hopefully, they would graduate to Lexus. Scion came up with the xB, which was a boxy car that was really meant for Japanese domestic market. It was small on the outside and rommy on the inside for the narrow Japanese streets. It had large square windows that had excellent visibility. It was lightweight with a small engine that gets great economy. What was unexpected was that it attracted older drivers who pushed sales up rapidly. After a while, the Scion brand started to become a cool brand because it had unique cars that were also practical.
Then came 2008 redesign. Scion made it larger, bigger engine and smaller window. The critical rear quarter visibility is now horrible. Larger heavier car requires a bigger less economical engine. Everything that made the original xB practical and cool is now gone. So what happened to sales? After 2008, the xB sales took a nose dive. Nobody talked about the xB anymore. In fact, the xB was the car that defined the Scion brand. In an effort to make it appeal to a focus group consumer, they made a car that is no longer unique, and was just like any other cars that has poor visibility, over weight, large and uneconomical. The new xB started to look like the Chevrolet HHR, which is similar to the infamous, would not be caught dead in it, PT Cruiser.
The re-design of the xB was so disasterous that it single handedly tanked the Scion brand. The brand name became toxic. When the long awaited remake of the 80's rear wheel drive drift king AE86 came out, Toyota gave it the Scion brand calling it the Scion FR-S to try and lift the Scion brand out of the doldrums. Even with all that excitement, the Scion version of the car was still considered a "wish I could afford a Subaru" car. The Scion brand was that bad!
Side impact requirement: FMVSS 214 - All the requirements here.
Forbes magazine article.
Best visibility cars:
90-93 Honda Accord
89-94 Subaru Legacy
94-99 Subaru Legacy