How to setup RBD Car Follow Path node with this "DOP" context?

That's a switch that is only useful for when the node is used in a SOP Solver used as a pre (or post) solve for a rigid body solver in DOPs.

When this is enabled, it only snaps the car in position at the first frame of the sim (or whenever the car appears in the sim), and from there the car's current position, advected by the sim, is used to calculate where it wants to be and how it should get there by adjusting attributes on the steering conetwist constraints and the hard motor constraints, and setting the targetv, airresist and drag attributes on the proxy geo in order to get a physically plausible result.

Switching the context to DOPs outside of that isn't helpful in any way since those attributes are only useful in the context of a bullet RBD simulation as well as it relying on the car's position being updated by an external process - the RBD Solver.

npetit  小号
That's a switch that is only useful for when the node is used in a SOP Solver used as a pre (or post) solve for a rigid body solver in DOPs.

When this is enabled, it only snaps the car in position at the first frame of the sim (or whenever the car appears in the sim), and from there the car's current position, advected by the sim, is used to calculate where it wants to be and how it should get there by adjusting attributes on the steering conetwist constraints and the hard motor constraints, and setting the targetv, airresist and drag attributes on the proxy geo in order to get a physically plausible result.

Switching the context to DOPs outside of that isn't helpful in any way since those attributes are only useful in the context of a bullet RBD simulation as well as it relying on the car's position being updated by an external process - the RBD Solver.

Thank you for reply ,I have setup a simple scene, but result looks incorrect . Am I wrong?

There is a RBD Car Follow Path DOP which handles this for you.
You can dive inside to see how it's setup.

The problem you're having is you need the SOP Solver to use the invoke compiled block option so you can operate on both the geometry and the constraint geometry at the same time. Use a SOP Solver (Constraint Geometry) DOP - this sets it up for you.