Authors: Donald MacKenzie; Stephen Zoepf; John Heywood
Addresses: Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA ' Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA ' Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA
Abstract: After a precipitous drop from 1976-1982, the weight of US passenger cars has grown steadily. This article examines multiple conflicting influences on vehicle weight in two categories: technological changes that reduce vehicle weight and improvements in functionality that, ceteris paribus, add to vehicle weight. The widespread adoption of unibody construction, lightweight materials and smaller engines has been offset by growth in vehicle size and feature content. The best estimates from this work indicate that new features and functionality would have added at least 250 kg (550 lbs) to the weight of the average new car between 1975 and 2009, if not for offsetting improvements in technology. Over the same period, it is estimated that alternative materials, more weight-efficient vehicle architectures and reduced engine sizes have taken 790 kg (1700 lbs) out of the weight of the average car. These observable influences do not explain the full extent of the drop and subsequent growth in weight, suggesting that substantial non-observed technological improvements were made from 1976-1982 and that unobserved improvements in areas such as crashworthiness and NVH have added substantially to vehicle weight in the past two decades.
Keywords: passenger cars; vehicle weight; lightweight materials; unibody construction; vehicle features; vehicle design; technological change; functionality improvement; vehicle size; alternative materials; crashworthiness; NVH.
International Journal of Vehicle Design, 2014 Vol.65 No.1, pp.73 - 93
Received: 13 Jul 2012
Accepted: 02 Dec 2012
Published online: 26 Feb 2014 *