4.6.3* Parking Spaces.Accessible parking spaces shall be at least 96 in (2440 mm) wide. Parking access aisles shall be part of an accessible route to the building or facility entrance and shall comply with 4.3. Two accessible parking spaces may share a common access aisle (see Fig. 9). Parked vehicle overhangs shall not reduce the clear width of an accessible route. Parking spaces and access aisles shall be level with surface slopes not exceeding 1:50 (2%) in all directions.
I added to my reply earlier. Please reread.
I've found that this is really up to interpretation. You must consider where one can travel within the handicap designated area. For example, you wouldn't travel from one end of a ADA designated parking area to the other at a diagonal. With that said, if the field inspector is of the belief that it is indeed ALL directions then it would be best to grade the area as such to protect from and liability issues that may arise. Their is nothing "beau" about beauracracy. This subject came up in my office just this morning.
Make no mistake, the code is clear in this realm.
No greater than 2% in any direction throughout the handicap parking spaces.