Want to keep your engine running like new? Vehicle additives promise to clean your engine and exhaust internals, but are they actually worth your hard-earned cash? We find out. Plus, don't miss our massive guide exposing the biggest motoring scams out there today! We also pull the fuel injectors from our project Volvo XC90 for professional testing; demonstrate the rustproofing techniques using Lanoguard; troubleshoot a tricky ABS issue on a 2019 Peugeot Partner 1.6 HDi; and give you the ultimate buyer's guide to scoring a brilliant BMW 6-Series.