Tuesday, September 23, 2014

Characteristics of cars -- 2003 to 2013.

Question:   How have changes in the market for new cars varied across car weight class between 2003 and 2013?   What are the main limitations of this analysis?

Data:   The data for this exercise was obtained from appendix E of the 2013 fuel efficiency trend report.  


The EPA has a ton of data.   This problem focuses on two years (2003 and 2013) and four bits of information (levels of production, adjusted fuel efficiency, the size of the car in cubic feet, and horse power.)


Characteristics of New Cars
2003 and 2013
3000 lb Cars
Model Year
2003
2013
% Diff.
Production (000)
1775.523
1644.987
-7.4%
FE Adj
25.99927
31.06683
19.5%
Volume
104.358
107.5987
3.1%
Horse Power
133.0113
146.6017
10.2%
3500 lb Cars
Model Year
2003
2013
% Diff.
Production (000)
4119.23
3384.598
-17.8%
FE Adj
22.5803
29.21793
29.4%
Volume
111.1129
112.2783
1.0%
Horse Power
184.7662
179.9535
-2.6%
4000 lb Cars
Model Year
2003
2013
% Diff.
Production (000)
1013.136
1756.082
73.3%
FE Adj
20.35752
24.53153
20.5%
Volume
114.0055
110.8744
-2.7%
Horse Power
233.4654
273.6813
17.2%
4500 lb Cars
Model Year
2003
2013
% Diff.
Production (000)
277.864
358.814
29.1%
FE Adj
18.91283
21.12377
11.7%
Volume
128.6386
114.8827
-10.7%
Horse Power
255.1844
351.1438
37.6%


Analysis:  The main changes in autos 2003 to 2013 are as follows.

Reduced sales of 3000 lb and 3500 lb cars and increased sales of 4000 lb and 4500 lb cars.


All groups realized increased fuel efficiency.  Largest change was for 3500 lb category.   Smallest change was for 4500 lb category.

Volume in cubic feet for 3000 lb and 3500 lb cars increased.   Volume in cubic feet for 4000 lb and 4500 lb cars decreased.   The decrease in volume for 4500 cars was non trivial.

Horsepower rose for all cars except 3500 lb cars.   Largest change in horsepower was for 4500 lb cars.

Concluding thoughts: In 1970s and 1980s, improvements in fuel efficiency were associated to downsizing into smaller unsafe cars like the Chevette.   The recent improvement in fuel efficiency seem to be more closely associated with improvements in technology; although the 4000 lb and 4500 lb cars did shrink in volume.  I am not sure why volume of 4000 and 4500 cars fell but this segment is affected by growth in popularity of SUVS.

Limitations:  This data looks at cars only.   Since most SUVS are classified as light trucks this post provides only a narrow snapshot.  I also did not include cars less than 300 lbs and cars greater than 4500 lbs.   My quick glance at the data suggested that inclusion of these segments would not have added much to the analysis and would result in some readers getting lost in the data.     


Readers who like this post must also look at my post documenting recent improvements in fuel efficiency.  

























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