Quote Originally Posted by Matt93SE View Post
The EPA standard is widely published with car specs. Is the SAE standard measurement as widely published and as easy to find?

I'm not trying to be argumentative here, just asking a question. It seemed a lot easier to find interior volume published than passenger volume.
Based on the information I could find, SAE provides a measuring standard under J1100, which has been updated periodically. 1984 version, for example, here. It defines how to determine "passenger," "cargo," and total "interior" volumes (the latter being the sum of the other two). EPA requires reporting of dimensions to the SAE spec, standardized to one particular year's standards. They don't - again, based on what I found - vary much, year to year, but manufacturers may quote their "official" spec based on whatever standard they choose. The "cargo" volume spec varies (obviously) for hatchbacks vs. cars with trunks, but the passenger number should rely on similar first principles within a year's spec.

The difference between a 2-seater and a 4-seater is, irrespective of the specifics of any given spec, something in the nature of 1.5-2.0x. It's not like there should be any hair-splitting required to make the distinction. Heck - a simpler proxy (number of seats for adults, roof height, whatever) can be the standard for our purposes. Or the STAC can make a list.

K