why are GMAC's interest rates so high?

[psywzrd]

I know this isn't H3 specific but I'm an H3 owner so that's why I'm putting this here (mods: please feel free to move). Anyway, I'm trying to figure out why GMAC's lease rates are always so high. I'm thinking about getting another GM vehicle (possibly a Denali or an Escalade) and I'd like to get a better deal than GMAC offers. Their interest rates always seem to be somewhere around 7 and a fraction on a 36 month lease while other automakers routinely offer much lower rates (I know for a fact that Audi is offering 1.2% on a 36-month lease for a Q7 right now). I paid 4.2% on an Infiniti FX35 a couple years ago which I thought was a bit high, but it's nowhere near as high as what I'm paying for my H3 (7.75% I believe). Anyone have an explanation here or a recommendation?