I have no idea about the percentage that you should strive for, but I can give you this suggestion: To the dealer, you are just $$$ to them, they don’t care about your feelings. Of course they don’t want to offend you and have you walk away bad mouthing their dealership. By the same token, they are in business to make $$$, no other reason. The people who work there make their salaries based on them selling cars for the most amount of money. They don’t wake up in the morning and go to work because they love their jobs, that may be secondary. They go there to make $$$!

Knowing this, don’t even think that they will be offended by your offer. They hear this on a daily-hourly-minute basis. You work hard for your money, you should try to keep as much of it in your bank account as you can. They are just cars. Mercedes will make more of them. They are not a rare commodity. The same goes for car dealerships. If you feel you are not getting a fair shake at one dealership, walk out the door and head to the next Mercedes dealership down the road or across town. Better yet, do it all via email and do it with 3 different dealerships. The one who gives you the best deal will be the one who gets your business.

Good luck !

I buy cars CPO and have never custom ordered a vehicle from new, so take this with a grain of salt. From reading on this forum what other people have gotten off MSRP from custom ordered, 7%-10% seems to be about the norm for a gen 2 vehicle. That being said, I think you should start out at 15%, but don’t be too disappointed if they come back much lower. Again, my suggestion is to pit a few dealerships against one another via email. You can do this in your underwear in the comfort of your own home. Once you go into a dealership, they will use many different tactics to wear you down.

You are in in a great position as who wouldn’t want your 4 new car business. But again, they aren’t going to give the cars away as they do have a profit to make. Throw out a lowball number and see what they say. And please, please, please do not think you are offending anyone.