Mesh Tricks

When using mesh physics there are a few things you can do to lower Second Life land impact score and free up more physics allotment.

The basic idea is to not set complex/detailed sculpts or mesh parts to be solid/convex hull but instead to use very simple shape prims set to transparent to create your solid surfaces.

A mesh linkset can have up to 255 links, but only a total of 32 land impact in convex hull shape prims. The root is always convex hull, which is another very good reason to use a standard cube prim for the root prim. The simpler the prim shape in solid/convex hull, the less land impact used.

This causes a problem if your have for example, four mesh tires that are 8 land impact each, and must be solid/convex hull, as linking them to the root will exceed 32 land impact in convex hull once the root is linked.

In the case of the four mesh tires that eat up all the convex hull allowance, the solution is to set the prim shapes to none for the tires (remove any solid, wheel, or tire keywords) and link in basic cylinders set to transparent and assigned the solid/convex hull shape. The simple prims will use far less land impact than the detailed visible sculpt/mesh.

Make your standard cube root prim as large as possible to protect the front, back, and sides of the vehicle from getting hung up on hazards, and keep your actual detailed body/engine parts as no shape, shielded by your invisible root.