PSP Remaster / PSN Re-release
A hybrid single-player + asynchronous multiplayer feature that leverages the original PSP’s ad-hoc spirit but modernized via cloud saves.
While "Download Rumble Racing PSP" directly suggests a piracy-related query (which I can't support), I can propose a for a hypothetical Rumble Racing revival or official PSP remaster on modern platforms (e.g., PS4/PS5, PC, or mobile with controller support): Feature Name: "Rumble Link Rewind"