I drive a 20 year old truck that gets categorically ABYSMAL MPG. The problem is, I only drive it less than 10k miles per year and at the cost of a new vehicle,

I drive a 20 year old truck that gets categorically ABYSMAL MPG. The problem is, I only drive it less than 10k miles per year and at the cost of a new vehicle, I doubt I would ever "come out ahead" by replacing it.