That is highly untrue. Many of the german tank on the western front after Normandy were poorly trained (often due to fuel shortages). The wehrmacht had significantly less mechanization than the brits or americans, and often still had to haul artillery and supplies around by horse! In terms of equipment on paper the Panther tank (standard medium tank on the western front post normandy) suffered approx 4x as much breakdowns as the Sherman. The Axis lost every one of their tank offensives on the western front (avranches, lorraine, ardennes. And they lost much of those battles without allied air support. Their K/D ratios are often inflated because they were typically on the defensive, whenever panthers attacked defending shermans, panther losses were much higher than sherman losses.
German army werent that bad when they fought the western allies in 1943-1945.
http://en.wikipedia.org/wiki/Battle_of_the_Bulge
Battle of the Bulge:
US Army losses: 89,500 and 800 tanks.
Wehrmacht losses: 67,200–100,000 killed, missing, captured, or wounded and 600 tanks.
http://en.wikipedia.org/wiki/Operation_Nordwind
Operation Nordwind:
US army losses: 29,000
Wehrmacht losses: 23,000
http://en.wikipedia.org/wiki/Battle_of_H%C3%BCrtgen_Forest
Battle of Hürtgen Forest:
US army losses: 33,000
Wehrmacht losses: 28,000
http://en.wikipedia.org/wiki/Operation_Queen
Operation Queen:
US army losses: 38,500 and 340 tanks.
Wehrmacht: more or less equal.
http://en.wikipedia.org/wiki/Battle_of_Monte_Cassino
Battle of Monte Cassino
Allied losses: 55,000
Wehrmacht losses: 20,000
http://en.wikipedia.org/wiki/Operation_Shingle#Initial_Landings
Battle of Anzio
Allied losses: 43,000
Wehrmacht losses: 40,000
http://en.wikipedia.org/wiki/Operation_Overlord
Operation Overlord
Allied losses: 226,386, 4,101 planes, 4,000 tanks
Wehrmacht losses: 400,000-450,000(mostly of them prisoners who were captured), 2,127 planes, 2,200 tanks
There were also minor battles inside germany where some small forces of the wehrmacht archived great results against the US army for example some Jagdtiger battle groups were very effective against US tanks and destroyed many of them.