I'm having some success with my key fob survey:
I was surprised, pleasantly, to find the NHW20 key fobs are at the
bottom of the 315 mHz band. There are several technical issues yet to
address but it looks like I may have the kernel of a key fob research
tool. This will address the "Bell the Hybrid Act", HR 5734, as well as
another effort aimed at back-over accidents.