Been wrestling with this for a couple days and can't find any examples or clear help.

As I understand the Docs the rbdcarfollowpath_preview node is to let you procedurally animate the rbdcar rig at a more accessible level than driving it manually or trying to keyframe acceleration and steering to get the action you want. Then the carfollow path node passes that data to the RBDCarDeform node via the bullet solver and you get your path animation with the full sim and deformation those node provide. BUT while both Follow Path works, Car Deform works, the Car Deform does not match the animation from the follow path, to be more precise it follows the path and has the deformations but does not match the speed of the followpath car.

I know followpath has the 'dops' mode but that doesn't seem to make a difference to either followpath or CarDeform.

TLDR; I want to use followpath but also get the deformation provided by RBDCarDeform.

Any insight or pointers are welcome.
Thanks!

The RBD Car Follow Path SOP animates the car rig along a path, no driving involved.

The RBD Car Deform is completely separate and has nothing to do with following paths or not, it simply deforms the chassis and tires.

When using the quick setup to dynamic follow path, it creates a RBD Car Follow Path preview and creates its DOP counterpart inside the RBD Bullet Solver, with channel references where applicable, so as to try and have the simulation match the animated preview.

The RBD Car Follow Path DOP uses wheel spin (on the wheels with motors) and target velocities to try and get the car to follow the path, however, as the car deviates from the animated position on the path, due to many factors, i.e insufficient tire friction or contact with the ground, terrain profile, unrealistic animation given the physical properties of the car etc... it has to adjust its intended target accordingly in order to prioritize following the path as opposed to its world space position - too much lag around a bend and the car would then start cutting across to make it to its animated position.

By default, the RBD Car Follow Path DOP is set to respect vehicle & turning maximum speed. This looks at the min/max speed set on the RBD Car Rig, the tire friction, response time, path curvature and current speed to adjust the vehicle's target velocities - this is to ensure the car doesn't end up rolling over in corners and doesn't exceed its user defined capabilities. This can lead to it lagging behind the animation.

The RBD Car Follow Path SOP will show areas on the curve where the car exceeds those limits in red.

Dive inside the RBD Bullet Solver and look at the RBD Car Follow Path DOP.

Lowering the response time will ensure the car reacts faster to changes in the path and its relative position to the animated position - the turns, accelerations and decelerations will be sharper for a more aggressive type of driving.

Increasing air resist and drag will also increase the influence of the calculated target velocities, at the expense of relying less on the effect of the motors on the wheels - it can lead to less plausible results in favor of matching the anim closer.

You can also turn off the respect vehicle & turning max speed option and the car will ignore all that and simply try to stick the the animation more, exceeding the speed limits where needed.

Thank you! Totally get it now. Appreciate this comprehensive answer.