[Christ]

Clean grounds do create less load on the engine, as well as cleaner signals and faster response time from the ecu.

Think of it from the perspective of current: easier to walk in water, or syrup? It takes more energy to walk in some substance that doesn't allow free movement, and it takes more energy to transfer current through a corroded write not making good contact.

This is actually something you might remember me suggesting occasionally as a good thingto check on a new to you car, as it can have an effect on fe. I generally recommend replacement with a cheap eBay battery ground kit.