I bought a new Toyota Tundra SR5 with upgrade package, 4WD, spray-in bed liner, side steps, 20" ultra motorsports wheels, etc., for $36,000 plus tax in December 2014. Sticker was $44,300, IIRC. They were also offering 0% for 5 years. I took it only after offering to write a check for $36,000 OTD (including tax). They said they couldn't, they were at rock bottom. This was 4 days before Christmas and this truck had been on the lot for 7 months. This dealer is in an area where 4x4 trucks are not hot sellers. nor were $40k vehicles. Let's just say their primary source of revenue was either long-term renting or leasing Corollas.
I think I did ok. I did take 58 months to pay it off, primarily because I told myself each month there was no benefit to paying it off early. My wife started in on me about year 4 and kept saying "we should just pay that off." I had to tell her there was no interest accumulating and there was no different payoff amount other than X number of payments left.
So there was not a cheaper price for me to pay cash or finance elsewhere with my deal. I can prove that by saying I kept up with fair market value of my truck for about 3 years. At about month 20, my truck was still worth about $33,000 on the street. That's a drop in value of $3,000 from what I paid for it almost 2 years earlier.
I'll probably never run into a deal like that again.
As far as the "deals" on GM vehicles right now, I'd take one if given to me, no way I'd finance one for 84 months, much less buy one for $1.