File:Car Quality Ranks of Detroit 3 and 5 Japan-Based Auto Manufacturers by Infrequency of Trouble-Prone Models.jpg

English: Line Chart of the Car Quality Ranks of General Motors Corporation, the Chrysler Group, Ford Motor Company, Toyota Motor Corporation, Honda Motor Company, Nissan Motor Company, Fuji Heavy Industires Ltd, and Mazda Motor Corporation by Infrequency of Trouble-Prone Models in Years 1980, 1985, 1990, 1995, 2000, 2005, and 2010

Ranking automobile manufacturers by infrequency of trouble-prone models provides a measure of how well each manufacturer's models successfully avoided the bottom end of the model-quality spectrum.

This ranking by quality uses two sections of the April issues of Consumer Reports - its Used-Cars-to-Avoid table and its reliability charts - and involves several steps.

To form a car-manufacturer quality measure from each of the annual lists of Used Cars to Avoid, the first step is to count each manufacturer's entries on the list. Each model year of each model is treated as a separate entry.

Next, as the number of automobile models sold by a car manufacturer varies greatly from maker to maker, it is necessary to take account of the fact that a manufacturer with more models has a greater opportunity to have more model years of low quality. To compensate for a possibly inflated, or deflated, frequency of trouble-prone model years of a manufacturer, as well as a variability in model data sufficiency, the number of a manufacturer's entries in a Used-Cars-To-Avoid list is divided by the total number of overall reliability columns for the manufacturer found in the reliability charts of the same issue of Consumer Reports.

Finally, the automobile manufacturers with at least 5 overall reliability ratings are ordered from best to worst for each of the years 1980, 1985, 1990, 1995, 2000, 2005, and 2010. The best manufacturer in a given year has a quality rank of 1. The worst quality rank varies from year to year and ranges from 13 to 19.

Automobile manufacturers with a rank in at least one year include American Motors Corporation, BMW AG, the Chrysler Group (previously Chrysler Corporation, the Chrysler Group of DaimlerChrysler AG, and Chrysler LLC, and presently Chrysler Group LLC), Ford Motor Company, Fiat S.p.A., General Motors Corporation, Honda Motor Company, Isuzu Motors Ltd., Jaguar, Kia Motors Corporation, Mazda Motor Corporation, Daimler AG (previously Daimler-Benz AG and the Mercedes-Benz division of DaimlerChrysler AG), Mitsubishi Motors Corporation, Nissan Motor Company, PSA Peugeot Citroën, Porsche AG, Saab, Fuji Heavy Industries Ltd., Suzuki Motor Corporation, Toyota Motor Corporation, Volkswagen AG, and Volvo.

For several of the above years, Saab was a division of General Motors Corporation and Volvo and Jaguar were divisions of Ford Motor Company; however, for all of the above years, they have been treated as separate companies.

General Motors Corporation encompasses its now bankrupt predecessor, renamed in GM's 2009 bankruptcy proceeding as Motors Liquidation Company.

For a Google Knol that summarizes the changes in car brand and manufacturer ranking by this quality measure from 1990 to 2010, visit http://knol.google.com/k/james-bleeker/automobile-quality-by-car-brand-and/3o3u27f0whd6k/2?hd=ns# .

For a Google Knol that summarizes car manufacturer product quality from 1975 to 2010, visit "Car Quality from 1975 to 2010 - A History of U.S. Automobile Manufacturer Quality Ranks" at http://knol.google.com/k/james-bleeker/car-quality-from-1975-to-2010-a-history/3o3u27f0whd6k/9# .