|
|
Toyota Age Equivalents
by James Bleeker
The following table provides the estimated ages of when a typical 1999
model by Toyota Motor Corporation will be about as troublesome as a typical
1999 model of selected other manufacturers and lines were at ages 3, 4, 5,
6, and 7 years.
Age Equivalent Estimates for Toyota Motor
Corporation
Estimated Ages of When a
Typical 1999 Toyota Motor Corporation Model Will be as
Problem-Plagued as Typical 1999 Models of Other
Automobile Manufacturers, Groups, and Lines Were at Ages
3, 4, 5, 6, and 7 Years
|
Manufacturer or
Group |
Line |
Estimated Age of
Toyota Model Corresponding to a 3-Year-Old Model of
Listed Manufacturer or Line |
Estimated Age of
Toyota Model Corresponding to a 4-Year-Old Model of
Listed Manufacturer or Line |
Estimated Age of
Toyota Model Corresponding to a 5-Year-Old Model of
Listed Manufacturer or Line |
Estimated Age of
Toyota Model Corresponding to a 6-Year-Old Model of
Listed Manufacturer or Line |
Estimated Age of
Toyota Model Corresponding to a 7-Year-Old Model of
Listed Manufacturer or Line |
Nissan Motor Company |
5 years |
6 years |
8 years |
9 years |
11 years |
Mazda Motor Corporation |
9 years |
11 years |
13 years |
16 years |
19 years |
|
Ford |
15 years |
16 years |
18 years |
20 years |
23 years |
|
Lincoln |
14 years |
16 years |
19 years |
22 years |
26 years |
|
Mercury |
15 years |
17 years |
20 years |
22 years |
26 years |
Ford Motor Company |
15 years |
17 years |
19 years |
21 years |
24 years |
BMW AG |
9 years |
12 years |
20 years |
24 years |
26 years |
Mercedes-Benz |
17 years |
22 years |
24 years |
27 years |
27 years |
|
Chrysler |
18 years |
22 years |
26 years |
32 years |
32 years |
|
Dodge |
17 years |
21 years |
24 years |
29 years |
32 years |
|
Plymouth |
13 years |
21 years |
24 years |
32 years |
33 years |
|
Jeep |
20 years |
23 years |
24 years |
26 years |
34 years |
Chrysler Group |
17 years |
22 years |
25 years |
29 years |
32 years |
|
Saturn |
8 years |
13 years |
17 years |
17 years |
17 years |
|
Buick |
14 years |
17 years |
20 years |
23 years |
24 years |
|
Cadillac |
22 years |
22 years |
24 years |
29 years |
32 years |
|
Chevrolet |
19 years |
22 years |
25 years |
31 years |
34 years |
|
Pontiac |
20 years |
24 years |
27 years |
30 years |
36 years |
|
Oldsmobile |
20 years |
25 years |
28 years |
33 years |
35 years |
General Motors Corporation |
19 years |
22 years |
25 years |
29 years |
33 years |
|
Audi |
15 years |
23 years |
27 years |
31 years |
33 years |
|
Volkswagen |
20 years |
27 years |
31 years |
38 years |
42 years |
Volkswagen AG |
19 years |
25 years |
29 years |
35 years |
40 years |
The computation of these estimated age equivalents is rather involved.
(While some PhD theses seem to have been thrown together in a Saturday
afternoon, the above estimates were not, as you'll soon see.)
What follows is, in the main, what appeared in a November 2007
article on AutoOnInfo.net.
We begin with the following
table of Reliability Score averages for model year 1999.
Note |
The above Excel table is the original
table from the November 2007 article, so it bears
the visual shortcomings of the graphics made by earlier Microsoft products. |
Next, we plot the Reliability Score
averages of Toyota Motor Corporation for each of the above age ranges
(2-to-4 years, 3-to-5 years, ..., 4-to-6 years) and make an extrapolation of
these plots, a linear regression of degree one. We will first determine an
estimate of when a typical 1999 model of Toyota Motor Corporation will be as
troublesome as a typical 1999 model of General Motors Corporation at about
age 3 years. To do this, we plot GM's Reliability Score average for the
first age range (2-to-4 years) and draw a horizontal line. For the x-axis,
we use the midpoint of each age range. We have:

The equation on the chart is
the regression equation for Toyota's extrapolation. From the
chart's extrapolation, we see the estimate of when a typical
1999 Toyota model may be as troublesome as a typical 1999 GM
model circa age 3 years to be about 19 years. By computation,
substituting GM's rounded Reliability Score average of .27 (for
age range 2-to-4 years) for y in Toyota's regression equation,
we obtain an estimate of 19.0 years. Another way of viewing the
result is: If a typical 1999 GM vehicle became unacceptable to
own by reason of trouble or risk of trouble at about 3 years old
(calendar year 2002 or earlier), then a typical 1999 Toyota
vehicle may become unacceptable to own at about age 19.0 years,
or circa calendar year 2018.
The next four charts depict
similarly derived estimates of age equivalents (with respect to
vehicular deterioration) for a typical 1999 model of Toyota
corresponding to approximate ages 4 years, 5 years, 6 years, and
7 years of a typical 1999 GM model.




From the charts, we see that
the estimates of when a typical 1999 Toyota model may be as
troublesome as a typical 1999 GM model at about ages 4 years, 5
years, 6 years, and 7 years are about 22 years, 25 years, 29
years, and 33 years, respectively. By computation, substituting
GM's rounded Reliability Score averages for y in Toyota's
regression equation, we obtain the following estimates of when a
typical 1999 Toyota model will be as troublesome as a typical
1999 GM model at ages 4 years, 5 years, 6 years, and 7 years:
22.4 years, 25.5 years, 29.4 years, and 33.1 years,
respectively.
Note that each succeeding chart
requires an extrapolation farther into the future and
consequently each succeeding age-equivalent estimate is less
certain.
By substituting the Reliability
Score averages for each of the manufacturers and lines into Toyota's
regression equation, we obtained the above table of Toyota
age-equivalent estimates, rounded to the nearest whole year.
With regard to the computation of Reliability Score averages,
I borrow the old summary:
The definition
of Reliability Score begins with two observations. First, the
symbols in the right-most column of a Consumer Reports
auto model reliability table depicts reliability performance of
categories (called “trouble spots,” by Consumer Reports)
of components of motor vehicles in the approximate age range of
0 to 1 year – the exact age range depending upon when the
corresponding model year began and ended and when Consumer
Reports stopped accepting returned questionnaires for its
compilations. Second, similarly, the second column from the
right, the third column, the fourth column, the fifth column,
the sixth column, the seventh column, and the eighth column
depict reliability performance of the same categories of
components in the approximate age ranges of 1 to 2 years, 2 to 3
years, 3 to 4 years, 4 to 5 years, 5 to 6 years, 6 to 7 years,
and 7 to 8 years, respectively.
Next, some
particular Reliability Scores are defined, from which may be
seen a general definition. The Reliability Score RS(The
Lexus LS400,1991,7-8)
was obtained as follows:
1.
The leftmost column of the Lexus LS400 reliability table
in the April 1999 issue of Consumer Reports was selected,
as it is this column that rates problem frequencies by “trouble
spots” in the 1991 Lexus LS400s that were in the
age range of 7-8 years, approximately.
2. The
trouble spots of “Manual Transmission,” “Clutch,” “Brakes” and
“Exhaust” were eliminated from this left-most column for reasons
discussed in step 1 of the foregoing definitions of Reliability
Index Value and Average.
3. If
all of the remaining 12 trouble spots had a Consumer Reports
rating, the following was done. First, -1 was ascribed to each
of those trouble spots that earned the lowest rating (had the
highest frequency of reported auto problems.
Second, - ½ was ascribed to each of those trouble spots that
earned the second lowest rating (had the second highest
frequency of reported auto problems.
Third, 0 was ascribed to each of those trouble spots that earned
the middle rating (had the third highest frequency of
reported auto problems.
Fourth, + ½ was ascribed to each of those trouble spots that
earned the second highest rating (had the second lowest
frequency of reported car problems.
Fifth, +1 was ascribed to each of those trouble spots that
earned the highest rating (had the lowest frequency of
reported auto problems.
Next, the numbers that were obtained in 3 were added
together and divided by 12. This value is the Lexus LS400’s
Reliability Score:
RS(The Lexus LS400,1991,7-8).
Rather at once, it is seen that this value falls in the
closed interval [-1,+1], as is the case for all Reliability
Index Values.
While the above computations are for model year 1999, they
likely apply to more recent model years as well, since changes
in quality occur at a rather glacial pace. See
Charts of Annual Shares of Consumer
Reports' Used Cars to Avoid.
As the above computations are quite involved, they are not likely
to be duplicated soon, and updating for more recent years is
additionally complicated by the possibility that Consumer
Reports may have changed the definitions of the symbols it uses,
which would require an additional examination to determine
whether the change, if any, is significant with respect to
maintaining uniform Reliability Scores.
Disclosure |
Site manager is currently a
very small shareholder of Ford Motor Company (2010-04-27). I am not,
and have not been, a
shareholder of any other motor vehicle manufacturer. |
A
PDF file of this page is available for downloading.
Note |
Although this site was created using software by Microsoft,
you may encounter difficulty in downloading a PDF file from this
page using
Internet Explorer. However, with Mozilla Firefox, there should
be no difficulty, and the download should be speedy. |
AutoOnInfo.net: The auto-quality website with the
Open Directory Cool Site Award.
|