At last check, a car without windows has not yet appeared, but carmakers are trending toward smaller windows that seem to restrict visibility. Models with low rooflines, high sills, sharply sloping windshields, large door pillars and heavy tints are widely offered and based on hot models such as the Chrysler 300, Nissans Z and even the Prius consumers like the look.
But auto safety experts and many consumers say the design trend, along with other features that restrict forward and rearward visibility, are compromising safety.
We are very concerned about the visibility issue, both sideward visibility and the vertical height of windows, as well as the sweep of the windshield, said Judie Stone, president of Advocates for Highway and Auto Safety. There need to be federal standards.
The problems Stone lists are well-known to many drivers, particularly those who fall far outside the median heights for men and women.
Miriam Schulman, who stands 5 feet tall, says some car designs restrict her visibility, including her husbands prized Saab that she recently dented because its high rear shelf blocked her view when backing up.
There are models of cars that I would never buy because I can hardly see over the steering wheel, said Schulman, who has written about ethical issues involving the medical treatment of short people in her job at the Markkula Center for Applied Ethics at Santa Clara University.
Design experts say the trend toward more complete enclosure of passengers enhances a sense of safety and security, which are issues on the minds of many Americans.
It could be the war in Iraq, lingering fears from the terrorist attacks or freeway shootings, but many motorists feel exposed to more than normal risks on the highway.
People feel more protected in a vehicle with smaller windows, said Stewart Reed, chairman of transportation design at the Art Center College of Design in Pasadena, Calif. That is one trend for SUVs. People feel more secure in them.
By contrast, 1980s-era designs opened up the passenger compartment, putting drivers in a glass bubble. The eras minivans surrounded occupants with glass.
In the 1980s, the belt lines were getting lower and the cabin higher, lighter and airy looking, Reed said. Clearly, it was better visibility then.
Models such as the Nissan Murano, Dodge Magnum and Hummer H2 and H3, among many others, have adopted the small-window look.
But if visibility plays a role in a vehicles safety record, it is difficult to extract from crash statistics. Take, for example, the sleek-backed Murano. It has below-average collision and injury rates, according to data compiled by the Insurance Institute for Highway Safety.
Why one vehicle crashes more than another involves a complex suite of factors, including the kinds of drivers who own the vehicles, the stability of a vehicle and visibility, among many other elements. Trying to pull one factor, particularly a human one, out of the mix is difficult, if not impossible, says Russ Rader, a spokesman at the Insurance Institute.
The National Highway Traffic Safety Administration has never examined the role vehicle visibility plays in fatal or injury accidents, according to agency spokesman Rae Tyson.
Indeed, the federal government has no regulations that apply to window size, according to Richard Van Iderstine, the federal governments longtime visibility guru who retired from the NHTSA last year.
There is no regulation that windows even have to exist for a passenger car, he noted. There is only the presumption they exist.
Although small windshields and side windows may seem like they reduce visibility, thats not always the case. In some vehicles with low-slung windows, the drivers head position offers normal vision out of the window, Van Iderstine said. But on the other hand, drivers well above or below average height could have a greater problem adapting to a car with smaller windows.
Other issues associated with visibility -- window tinting, the size of rearview mirrors and the visibility out the rear window -- are equally subject to design trends. Reed worries that many of the advances made in reducing glare and eliminating other visual distractions from the drivers field of view, particularly near the top of the instrument panel, are being lost.
I see a trend by all the worlds manufacturers to go back to a lot of visual activity up there (on dashboards), he said.
Among the biggest problems for short individuals is rearward visibility, particularly in SUVs and other big vehicles. Last year, more than 100 children were killed when they were run over by vehicles backing up, driven in many cases by their parents, according to Janette E. Fennell, president of the advocacy groups Kids and Cars.
A study by Consumer Reports on the problem found that the rearward blind spot for some large SUVs and pickup trucks extended up to 50 feet behind the vehicle, measured by when a 5-foot-1 inch driver looking out the rear window could see a 28-inch traffic cone.
To deal with the problem, some manufacturers are offering rear-facing cameras or radar-based warning systems. Other new systems signal if there is a potential collision during lane changes.
Beyond styling, a lot of factors affect visibility. The increasingly sharp sweep of windshields to improve aerodynamics has forced engineers in some cases to increase the size of forward window pillars, creating somewhat larger blind spots.
Another structural issue that drives the size of pillars is the growing demand of safety advocates for greater resistance to roof crush in rollover accidents, said Robert Cavin, an analyst of advanced technology at the market research firm Frost & Sullivan. The enclosed feeling is creeping up, he said.
Sharply sloping hoods, another trend fostered by efforts to improve fuel economy, create another visibility problem. In some vehicles, it is virtually impossible for drivers to perceive the edges of the vehicle and the fenders almost disappear from the sloping hood.
Many drivers exacerbate visibility problems by failing to properly adjust their side-view mirrors, says Van Iderstine. Typically, drivers adjust those mirrors so that their own vehicle is within view, providing a frame of reference. Instead, he says, drivers should adjust the mirrors almost as far outward as possible, so that a vehicle in the adjacent lane will just come into view of the side mirror as they are passing out of view of the center inside mirror. Then, those vehicles in adjacent lanes will remain in the view of the side mirrors until they come into the drivers peripheral vision. With a little movement of the head, all of the blind spots can be eliminated, Van Iderstine says.
But mirror adjustment remains highly controversial. The California Highway Patrol, for instance, requires that officers look over their shoulders, rather than rely on mirrors.