I use the MSRP and then discount that by 10% to 16% for an (out the door price) with tax, lic. , doc, rebates included.
Example: MSRP 48,520 - 12. 4% = 42,500 (out the door). My nephew just bought a 2008 Ram 3500 Quad cab, SLT, SRW, 4 wheel dr. auto, turbo diesel 350/650 for 42,500 out the door !
The last three new vehicles that I was involved with has been this way.