Yep.I'm with you. Yep, money is fungible.
Rough prices for the models:
SE - 7500/40000 = 19%
XSE - 7500/50000 = 15%
only a 4% difference, right? Nope, try 4/19 - 21% difference, when comparing the tax credit for an SE vs XSE.
An SE is 90% of the car of an XSE, yet 25% less.
*this is how I run numbers comparing models and vehicles - YMMV for people who want "premium" features
For me, after all credits, the calculation is this:
7500/31500 = 23.8%. I get a full $10k in combined state / fed credits, so my bottom line cost is only a little under $31,500.