My experience with buying off the lot and ordering:

Generally speaking, from the time a new model year car is introduced to a month or two before year end, ordering may be a better financial bet as the dealer has no inventory carrying costs as they would for a lot car that's been sitting around for some time. 2014 models will likely have a modest increase in price when the pricing is announced based on previous years.

As the model year comes to a close and especially after the next year models arrive, negotiating a better deal on a closeout on-lot car is likely, although choices will be more limited. Often, the manufacturer will offer additional dealer incentives for last year cars to help move them out allowing for a deeper discount.

Note that If buying (vs. leasing) at the end of the model year, you will be purchasing a "year old" car for depreciation consideration, albeit with very low mileage during the first year of use. The lower mileage will mitigate some of the extra depreciation (but not all). Also, If the car is in high demand, the potential of deeper discounts either way can disappear.

As for the difference in dollars, it's not possible to quantify; each situation will be different. Audi Club of North America is offering a 6% discount off sticker on most 2013 Audis for those who are paid members for at least 6 months before delivery. It's been reported recently that they have renewed the offer to waive the 6 month requirement if a lifetime membership is purchased although some say this is not the case. There is no guarantee the 6% discount will be renewed for 2014 models. Prior to Feb, 2013, ACNA was offering only a $500 rebate. They usually don't announce the program until the new year models arrive. the same is true for Audi's Loyalty rebate. For the A6 it was $1500 for 2013 but no announcement yet for 2014. It was $2000 for purchase and $1000 for lease in 2012 and $1500 for both in 2013.