The car as we know it was designed in a world where the cost of oil was low. True efficiency in fuel consumption did not really matter. This environment created a certain set of expectations for the automobile and over time these expectations have grown. Some of these expectations have been mandated, such as air bags and emissions requirements. Others started out as options, such as heated seats, electric windows, and remote locks, that over time have mostly become the norm.
The result has been heavier automobiles. One way of looking at this is to compare two very similar cars. For example, the 1967 Porsche 911 and the 1995 Porsche 911 are virtually the same size, both are equipped with air-cooled 6 cylinder engines, but the 1967 version weighs 1000 lbs less. Similar power by displacement – both are about 80 hp per liter – but the 1995 Porsche has 3600 cc, compared to only 1991 cc in the 1967. A larger engine needed to move a heavier car.
Every time the very good engineers at Porsche found some way to make the car more powerful or more efficient it was lost by an offsetting entry in terms of emissions control, convenience features, safety improvements or simply needing to make the car stronger (ie, bigger and heavier parts) because the car weighed more or was more powerful.
So today we want doors on our cars that include electric windows, electric mirrors, sound deadening and so on. Doors that once weighed 40 lbs today can weigh over 120 lbs. Some of this weight comes from important improvements, such as side impact airbags and door beams, but other comes from features (requiring motors, wiring, brackets, switches and more space) that perhaps are not worth the energy and environmental costs.
Weight is a major factor in auto efficiency and feature creep is a reason why our society has made only minor advances in fleet efficiency. But the impacts of increased weight are not felt just in terms of mileage. A light car has less impact on roads, and is good news for pedestrians and bicyclists. It consumes fewer materials in production and in use – tires last longer, for example.
It is time to decide what we want and what we expect in a car, what is a necessity and what is a luxury. If as a country we really want greater efficiency and lower environmental impact some things need to change.