German forces did not enter Tunisia until late 42 in response to the “Torch” landings. Those forces were sent from Europe and were seen in a mix of repainted Panzer Gray vehicles (brown over gray) and a few in the new Dark Yellow color which started appearing at that time (before it’s official release). Afrika Corps units which survived the retreat from El Alamein to Tunisia were in whatever scheme they wore prior to the retreat.
As a general rule of thumb, vehicles repainted in Africa over the Panzer gray base color had existing markings masked off and a surrounding area of gray on the finished vehicle. Official memo’s for painting called for a 2/3 coverage of Yellow Brown or Brown with a 1/3 coverage of the Gray Green or Dark Gray color. Patterns were at the whim of the painter/soldier directing painting. Often times vehicles field painted recieved the overall sand color but with many areas (suspension, interiors of open topped vehicles, inner face of hatches) left in the original Panzer Gray. Vehicles delivered as replacements were often painted at the factory according to the official guidelines.