I managed to dig out one source on the motor transport situation for the Germans Referenced
Madej V, German War Economy - The Motorization Myth Allentown Publishing 1984
Agrees with the vehicle availability figures as at june 1941, Doesnt give a figure for total truck numbers in the west during the normandy campaign, but does say that lift capacity for the support echelons had dropped to below 1000 tons per day , and that the average supply distance by June 1944 for the forces in Normandy had increased to over 500 km, mostly because of the Allied Interdiction campaign. Somewhat offset by stockpiles that had been made prior to the campaign. However the average daily trip distance for german trucks, according to Madej was 150 Kms per day. Distance to supply heads 500 km. Thruput capacity of the supply echelon, about 1000 tons per day per div. Average load carrying capacity per truck might be about 2.5 tons tare (made low by the return trip to depot empty). To move that 1000 tons per day, you are going to need around 1500 trucks, just in the rear echelons, then there are the vehicles needed to get from the forward epoits to the front lines.....maybe 200-800 vehicles attached directly to the Div (say an average of 500 vehicles). On average, therefore, in June 1944, in the normandy front, you are looking at an average of about 2000 vehicles per Div. There are of course the Horse drawn elements, but these generally did not undertake the kind of long haul heavy lift supply efforts we are talking about. The majority of Horse drawn transport was used to get additional ammunition to the Artillery regiments and heavy weapons groups.
Saying that Normandy was a static battle is untrue, except for those Divs located within fortresses like Cherbourg. The Static did rely on stockpiled supply, but the units in the lines could not. and this was the majority of formations engaged in the battle. A better example of a static battle might be the Somme or Verdun, where front lines might change by a few yards every day. This was not the case in Normandy....front lines were constantly changing, Divisions were constantly moving about.....it cannot be viewed as a static battle from a logistics POV
At 1000 tons per day, in conditions of heavy engagement such as normandy, ammunition expenditure alone for a german infantry Div can be as high as 500 tons per hour, however according to Dunnigan on average you might expect a minimum of 1500 tons per day, plus about 500 tons per day for other consummables. I expect water and fodder for the horse drawn transport could be obtained locally (amounting to about 140 tons per day of that 500 tons ancillary items) . However its no wonder that the germans were on a more less constant restricted ammunition regimethroughout the campaign....they didnt have the supply capability to heavily engage their divisions all the time. The campaign had to have been a nightmare for them
I found figures which showed that at Normandy german troops supllied from 15 to 35% of ammunition spent previous period. So...