There are moments in life when you knowingly make a terrible decision. For some, it’s taking up golf. For others, it’s buying a gym membership in January. For me, it was buying a 2007 Audi A6 Allroad. A nearly 20-year-old German wagon with a 3.0-litre turbo diesel, air suspension, and enough potential mechanical issues to keep an Audi technician employed for life. Buying an old German luxury car is a bit like adopting a retired racehorse. It’…