Quick question about CPI for my macro course

I have a problem that talks about an antique chevy Model T costing 500$ in 1918 with the CPI base year 1983. The CPI in 1918 is 15.1, so the price level increased 84.9%. So the price at 1983 CPI is 500x1.849=924.5 and then at current prices (CPI=190) 924.5x1.90=1756.55. Now we all know a new car wouldn't cost $1700 at todays prices so WHAT accounts for the difference?

I know CPI uses fixed weights on goods so is that why the current price of the Model T is different than current prices of todays cars? In this case, the weight issued to Model T's in 1918 hasn't been adjusted so the price of the car isn't actually taking inflation into account...correct?

Thanks for any help you guys might provide

16 Comments
 

Are you trolling?

15.1 ---> 100 is a 662% increase.

When a plumber from Hoboken tells you he has a good feeling about a reverse iron condor spread on the Japanese Yen, you really have no choice. If you don’t do it to him, somebody else surely will. -Eddie B.
 

Of course its exponential, but I didn't want to introduce that since you're obviously very confused. 3.16% still isn't correct, but I'm glad you're on the right track.

What exactly is your question? IlliniProgrammer explained the actual difference in the vehicles. I pointed out your flaw in thinking the increase in CPI represents the actual percentage increase.

billfinance

I know the CPI base year is 100. 15.1 to 100 is an 84.9 increase so I concluded that as an 84.9% increase in price level.

SureThing

15.1 ---> 100 is a 662% increase.

Today's CPI is 233, not sure where you got 190. So 15.1 to 233 is a 1543% increase, bringing your $500 Model T to $7715. When accounting for lack of features like IP said, it pretty much adds up in my book.

When a plumber from Hoboken tells you he has a good feeling about a reverse iron condor spread on the Japanese Yen, you really have no choice. If you don’t do it to him, somebody else surely will. -Eddie B.
 
Best Response

A model T from 1918 was missing important things like, oh, power steering, power windows, cruise control, a 5 year warranty (let alone 1 year warranty), AC (let alone a heater), a metal roof, or more than 25 horsepower. They were also missing things like seat belts, air bags, crack-resistant windshields, etc etc. The list is endless.

A new golf cart in 1983 would have cost you about $3000. So yeah, CPI has done a pretty good job of tracking a dollar's purchasing power for a golf-cart like vehicle.

Your professor is an idiot. Either he's never seen a Model T before and decided to ask a question about it or he's an even bigger idiot for not noticing little details like the car being unable to go faster than ~45 mph. Why would you even ask this question in an econ class? (An early 20th century US history class, OK maybe)

Please, do me a favor and tell your professor that IlliniProgrammer thinks he's some combination of an idiot and an asshat.

Edit: looks like he's never ridden in a "Chevy" Model T. Seriously, where do they come up with these people?

 

And still...after all these posts...no one has really answered it yet. Illini I get what your saying but I don't think thats the answer hes looking for, something more to do directly with the CPI and how its calculated.

 

Today's CPI is 233 ya, my homework problem is hypothetical and thats why they list the CPI as 190. I know the answer for this question has to do with the weights of how CPI calculates items from a century ago, not anything to do with the car having alot new features nowadays (even though this is correct too).

 

Well, hope you got it then.

When a plumber from Hoboken tells you he has a good feeling about a reverse iron condor spread on the Japanese Yen, you really have no choice. If you don’t do it to him, somebody else surely will. -Eddie B.
 

I think you need to go New CPI / Old CPI x Old price to get your "new price". Pretty straight forward - if the car was $500 with CPI 15.1, it would be 100/15.1x500 = $3,311.26 for 1983 and 190/15.1x500 = $6,291.39 for current price (190 in your problem)

15.1 to 100 will never be an 84.9% increase...

 

Aut voluptatem eos aperiam nostrum. Enim assumenda nemo hic earum libero voluptate. Et rerum at totam veritatis qui aspernatur.

Maiores consectetur nemo perspiciatis. Dignissimos commodi ut iusto consequatur laboriosam est. Molestiae sed dolor architecto et debitis.

Career Advancement Opportunities

May 2026 Investment Banking

  • Evercore 01 99.4%
  • Moelis & Company 01 98.8%
  • JPMorgan 01 98.2%
  • Guggenheim Partners 01 97.6%
  • Morgan Stanley 07 97.1%

Overall Employee Satisfaction

May 2026 Investment Banking

  • Moelis & Company No 99.4%
  • Morgan Stanley 01 98.8%
  • Evercore 01 98.2%
  • BMO Capital Markets 12 97.6%
  • Banco Santander 01 97.0%

Professional Growth Opportunities

May 2026 Investment Banking

  • Moelis & Company No 99.4%
  • Evercore No 98.8%
  • Morgan Stanley 05 98.2%
  • JPMorgan No 97.6%
  • BMO Capital Markets 12 97.1%

Total Avg Compensation

May 2026 Investment Banking

  • Vice President (14) $434
  • Associates (43) $259
  • 3rd+ Year Analyst (8) $210
  • 2nd Year Analyst (22) $179
  • Intern/Summer Associate (13) $156
  • 1st Year Analyst (75) $151
  • Intern/Summer Analyst (65) $101
notes
16 IB Interviews Notes

“... there’s no excuse to not take advantage of the resources out there available to you. Best value for your $ are the...”

Leaderboard

1
redever's picture
redever
99.2
2
kanon's picture
kanon
99.0
3
Secyh62's picture
Secyh62
99.0
4
BankonBanking's picture
BankonBanking
99.0
5
DrApeman's picture
DrApeman
98.9
6
Betsy Massar's picture
Betsy Massar
98.9
7
CompBanker's picture
CompBanker
98.9
8
dosk17's picture
dosk17
98.9
9
GameTheory's picture
GameTheory
98.9
10
Jamoldo's picture
Jamoldo
98.8
success
From 10 rejections to 1 dream investment banking internship

“... I believe it was the single biggest reason why I ended up with an offer...”