Grandpa brags that he paid 3,730 in 1970 for a Mustang 2 door fastback boss-302. In november 2020, he can sell that car for anywhere from $83000 to $136,200 which he tells you is a return in the 100 s of percent by his math.

you know a little something about economics. in micro economics we use an inflation adjustor to express a good sold in 1970 to comparable price in 2020. So expressing a 1970 purchase in October 2020 dollars gives me a price of about $25,600.

Suppose your grandpa suggests to you that he is willing to gift you the money to purchase 2007 Jeep Grand Cherokee SRT8. He proposes that for about $30,000 you can get a similar deal to what he did with his 1970 Fastback.

How can you respectfully decline his offer using Micro Economics Terms so he can understand your position? and how can you make an argument that grandpa might have earned a greater return on something else?