It looks like registering my vehicle on the GE application and getting it inspected at a border station (San Ysidro and Otay Mesa are my closest interview centers anyway) effectively extends SENTRI benefits to GE membership though: http://www.globalentry.gov/faq.html#g2

Not that that would be automatic for every GE member, of course, but for somebody close to the southern border I'm not really seeing how it might be more beneficial to apply for SENTRI over GE. I'm pretty sure GE is even open to Mexican nationals at this point too.

On paper it looks like once vehicle registration is brought into play it's the exact same program under another name, which is causing me to wonder why the fee structure is different. Grandfathered-in policies, maybe? That seems to be the case with NEXUS.

I think I'm just paranoid that I'm missing some fine print somewhere, haha.