This is the website I use.
www.fightingchance.com
They give you more than just invoice pricing, rebates, etc. They also give you a run down of how that manufacturer has been doing recently as far as car sales and some other important ammo for you during negotiations, and they give you a strategy for those negotiations.
Their package is well worth the money (about $40). I used it when we bought my wifes 07 4Runner, and no lie, we ended up about $750 BELOW invoice. I know it sounds like an advertisement for them, but it really works, and it was so much easier than haggling with someone on a showroom floor.
However, this is quoted directly from their website:
"
Note also that there are always a few vehicles that are almost impossible to deal on because the demand is greater than the supply. For example, we have not heard from any people who have paid less than the full sticker price for the MINI Cooper, so paying us for information on this car would be a really dumb idea.
We also don't list Scion vehicles. With just $637 to $810 profit built into the sticker price, spending the time conducting a competitive bidding process on these cars probably wouldn't save you enough money to make it worth the effort. Also, we are frequently reluctant to take your money for some all-new vehicles (like the all-new 2010 Toyota Prius) in the first few months they're available because supply is typically behind demand and we don't think dealers are dealing much off the MSRP. In addition, we won't take money for Saturn vehicles, which have always had a no-****er price policy."