Movable rear wheels

[GasSavers_maximilian]

While looking into it I discovered that passive rear wheel steering is actually in use by a few manufacturers to compensate for oversteer. Handling and stability motivations so no data on tire wear or efficiency impact that I could find though.

[kamesama980]

High speed active rear steering allows the car to better use the available traction from the rear tires.

Originally Posted by maximilian

While looking into it I discovered that passive rear wheel steering is actually in use by a few manufacturers to compensate for oversteer. Handling and stability motivations so no data on tire wear or efficiency impact that I could find though.

how passive? [enter cressida rant] my old Cressida changed the toe several degrees with suspension articulation. not really passive but resultant. basically as the body rolled (as with hard turns) the rear would steer toward the outside of the turn effectively giving a little oversteer without the loss of traction normally associated with it. the result was pretty nice handling for as soft as the springs were (because the softness of the springs allowed the articulation that improved the handling) the downside however was that if you loaded the tits out of the car (or lowered it), both sides toe'd out and wore the tires really bad, really fast.

[GasSavers_maximilian]

Wikipedia actually has a short summary, which puts together all the stuff I was seeing around. Wish I'd just gone there first. No mention of impact other than handling there either.

Typical methods of achieving compliance understeer are to use a Watt's Link on a live rear axle, or the use of toe control bushings on a twist beam suspension. On an independent rear suspension it is normally achieved by changing the rates of the rubber bushings in the suspension.

[GasSavers_maximilian]

I looked up four wheel steering in The Fundamentals of Vehicle Dynamics and only handling and stability concerns are mentioned. Since that book is pretty complete, I suspect this means there is negligible impact on wear and fuel economy.