You are correct in that the polar moment of inertia is a factor in a car’s handling. And whether or not you are putting power through the drive wheels as well. But the moment of inertia is a constant, determined by weight distribution and as such not determined by torque to the wheels. I guess that statement threw me off.
In any case, let me add that I do *not* recommend coasting downhill in neutral. That we can agree on. There are, of course, many factors affecting your car’s behaviour when driving through a curve. What it comes down to (the limiting factor) is always how much force (forward/rearward/lateral) the tires are able to handle. When you add torque through the drive wheels while close to the limit of adhesion, you’ll get understeer on a FWD car and oversteer on a RWD car. Neither of which you’d really want (unless showing off for friends...:-)) which is why I scoffed at your ‘torque’ statement. But I realize you probably weren’t talking about a ‘close to the limit’ situation.
Drive safely and have a great day!
You’re right about the way I worded my original posting; the polar MOI is constant — unless you do some serious weight shifting in the vehicle.