My husband is on his third Mercedes-Benz ML. His current ML350 is now three years old and he is starting to look for his next car. He thinks this ML350 has been his best car ever - we use it for family holidays in France, ferrying teenage boys and their gear, and for towing a couple of trailers related to our smallholding. He has heard the Porsche Cayenne diesel compares favourably with the ML and has visited the showroom and collected information that suggests the fuel consumption is better and emissions are lower on the Porsche. He can be impulsive and, knowing how much he loves his ML, my concern is that he will commit to change, then regret it. Should I encourage him?