Im looking at a 2002 BMW 745i with 145,000 miles. Are these reliable? Its a carfax 1 owner corporate vehicle. What goes wrong at this mileage? I do all my own maintenance. Thank you!

2002 was the first year for the E65/E66 chassis. The first two years of this chassis were not very good cars as "bugs" still needed worked out.
One thing to keep in mind is that these cars new were $80,000 and although they can be now purchased for as low as $15,000, the cost to repair these cars are still equal to the $80K vehicle.