Size of the second hand car market in the US

Hi there,

You'll learn a lot more from this by trying it out yourself first! Why don't you post your approach here and we can provide commentary?

How to approach market sizing

It's very simple: Do the approach the is the easiest for you given the question.

Are they asking you to estimate something where you don't even know where to begin from the top (maybe you have 0 clue as to the market size of the industry, the GDP of that country, etc. etc.)? Then do bottom-up!

Alternatively, does it seem impossible to do a realistic from-the-ground-up estimation of something (perhaps it requires just far too many steps and assumptions)? Then do top-down!

Fundamentally, you need to take the approach that just makes the most sense in that circumstance. Quickly think about the key assumptions / numbers required and whether you 1) Know them or 2) Can reasonably estimate them. If you can, go ahead!

An Example

He's a Q&A for a great market sizing question here asking to estimate # of electric charging stations in a city in 10 years:

https://www.preplounge.com/en/consulting-forum/how-would-you-solve-this-market-sizing-question-from-roland-berger-7631

This one could be answered top-down (as I did) by estimating population of the city, # of drivers/ cars, etc. etc.

OR, it could be answered bottom-up by estimating # of stations you see per block (or # of gas/petrol tanks), % increase this might be over time (or # of EV stations that would be needed per gas tank given EV stations take 10 times as long), and # of blocks you'd estimate the city to have.

Take a look here for additional practice! https://www.preplounge.com/en/management-consulting-cases/brain-teaser/intermediate/taxis-in-manhattan-market-sizing-229

There are many alternative ways to solve this. And you improve much more by trying by yourself than by just reading answers.  

I suggest you give it a try and then we can comment and suggest improvement opportunities.

However, I don't want to leave you without even giving a hint. I suggest you consider:

• the number of cars in the US
• how long does a car last (you can think about how many miles divided by miles per year… or just assume reasonable number)
• how frequently one changes cars
• divide between those purchased new vs. second hand
• the different value of cars when purchased new
• the depreciation of the cars as the years pass by

(editiert)