We have a 2003 G500 which we have had for 5 years. Usual problems here and there but overall very happy with the G500. I am a point where I need to decide whether to buy a new car or keep this one. I prefer to keep this one but it has 150000 miles. Does anyone have any opinion on what is a realistic number of miles to expect out of a "well maintained" G500 V8. Any other issues/things to consider. In addition, if the engine was to need to be replaced/rebuilt the cost and difficulty of doing so? Advice appreciated.