All they can do is say no, which they prob will, its pretty far from the price you are working with.
With the other dealer, did u get a quote for the sale price on the g car or just the trade in? BTW, invoice is closer to 34k on that car with the options you listed.

Dont ever be afraid to ask for a price, ive had some flat out laugh at me when i told them the prices i was seeing from other dealers.

Check out edmunds, their prices paid forum has dedicated threads to each car, including the g35. You will find 1000-1500 below invoice on 05 to be very common in metro areas.

Back to your deal, i really dont like the fact they are padding yer tradein to cover their high sale price, it just sounds fishy to me, like they're gonna weasel out of the tradein price later, but stick you with that high sale price.

 

Considering at this time of year and with 06 already out for 6 weeks, 1k~1.5K below invoice isnt lowballing at all on the 05's, specialy most of ppl were getting 500 above inovice for at least last 7 months.

 

If they ever do that? I would hope he would have enough sense to walk away...would you rather perferr dealership offer you low sale price and low balling on your trade-in? either way it doesnt really matter, cus they gonna add the difference of the trade-in to the loan amount anyways