If you're feeling uneasy about the discrepancy in square footage numbers, it's understandable.

Does anyone know a reason for the discrepancies between owner data, if I should trust the Driving for Dollars app data or the county record data?

I found discrepancies in the sellers disclosure and what was actually in the home.

For example if it’s 12 weeks for permit we will carry 20 weeks in our proforma.Also every proforma should have contingenciesIf it’s multifamily where I have seen the biggest discrepancies in my experience has been absorption rates.

It has also caused billing issues or discrepancies, costing me extra work to keep in good standing with our providers.

There's often discrepancies between the two regarding square footage because the listing agent sometimes includes finished basements that the County assessment office doesn't recognize.  

I'm not sure why there is such a discrepency using Google's pagespeed tool and lighthouse in the chrome browser incognito mode.

The reason is for the discrepancy is because of the question you asked

Understanding or proving a value discrepancy of 10k to 30k is much more difficult… but if every other similar home is selling for $200k to $240k and yours is at $140k then there is something completely wrong here… What are other homes selling for in the area?

Thanks, @Chris Seveney, I have done that to some extent, but while I was working on my property analysis spreadsheet, I noticed the somewhat large discrepancies in my various CapEx calculations (based on the standard formulas) and became interested in finding a formula that I could use easily (back-of-the-napkin), without itemizing and predicting expenses, and that would work even in cases where the gap between ARV and Current Property Value are rather wide.