Here in Canada my Professional Accounting association receives a discount from Mercedes Benz Canada of $500 Cdn on 2020 GLE’s The discount is applied before taxes. This amounts to <1% discount - but every bit helps.

 

I was just in the market in early July, here in the SF Bay Area.
The rep offered me 11% off of a GLS450 he had on the lot without me trying to negotiate.
I had to custom order as they didn't have what I wanted on the lot. I worked with 3 local dealerships.
I was able to negotiate 8% off a custom ordered GSL450, and 6% off a custom ordered GLS580.
Two of the three local dealerships would agree to 8% off a custom ordered GLS450. Only one would do 6% off the custom ordered GLS580 - both of the other two wanted MSRP for the GLS580.

All of the above are dealer discounts - factory and other incentives are in addition.
I ended up ordering a GLS580.
When I debriefed with the reps who lost, both told me they could not have matched 6% off a custom GLS580 - so I felt good about the deal.

 

Up to 15% off custom orders for 450 in UK