Vehicle handling
Open it from the Game rail item. K3 Studio lists every vehicle it finds in the handling.meta files of your workspace.
Beginner mode
About ten sliders in plain language (top speed, acceleration, gears, grip, steering angle, slide when cornering, brakes, weight, ride height, damage). Each one maps to CHandlingData fields, shows the raw field and value underneath, has a tick at the stock value, and has its own reset.
Presets
Faster, More grip, Drift, Heavy, Arcade, Realistic and Police pursuit. You can stack them and undo them, and fine-tune every slider afterwards.
Expert mode
Every field, with its raw name and stock value, plus checks that compare fields (for example traction min higher than max).
Flags
Handling and model flags are checkboxes, and K3 Studio writes the hex value for you.
Saving
Save writes handling.meta. If the manifest is missing the HANDLING_FILE data_file and file entries, K3 Studio adds them, then ensures the resource.