The 2004 V70 2.5T geartronic transmission shifts into neutral while coasting after a 10 second or so delay. The car is designed to do this to save engine wear or somehow reduce emissions or somehow operate with more fuel efficiency. This may make a perverse kind of sense to someone, but not to me. Can this parameter be modified by reprogramming something? How do I shut this "feature" down? I'm mainly concerned with long downhill descents.

Dont they have a "3" and "L" setting? On "3" the gearbox never goes to 4th gear. On "L" it stays on 1 and 2 gear. This is for downhill driving.

That is the start of someting new.Just wait a couple of years and your engine is going to shut off when you stop a traffic light. like a golf cart all you will need to start will be push on the gas pedal. Emissions!!