Nope. You know what you want and don't want. It's the delaership's job to sell you a car that has what you want, and doesn't have what you don't want. Tell them thank you, they can either sell you the car equipped the way you want it, or another dealer will.

Of course, in my experience having something you don't want can be a negotiating position in your favor. Perhaps you would be willing to accept the car with the NAV system if they throw in some other stuff at no cost (oil changes, extended warranty, etc. etc.). It all depends really on how much you don't want that option, how much they want to move the car, and what they're willing to do for you in order to get you to take the car they have. Check back with them the last week of the month, when they're trying to make sales quotas for the month, dealerships are usually more likely to 'deal' at the end of the month so they can get the car off their books before the first of the next month.