That’s a tough call. Your commute is pretty short and one of the worst things you can do is let a vehicle sit too long. On the other hand I’m sure cost of maintenance is more on the Chevy, especially if it’s a diesel. Tires alone can set you back near $2000 these days! I have a commuter truck (1991 Nissan d21) that is cheap to maintain, easy for me to work on, and I don’t feel bad when I rack up my 300 miles a week. My tow rig (2016 powerstroke) gets driven a couple times a week and is usually hauling or towing something as it was meant for. So I guess I’d say keep the commuter and prolong the trucks life, but make a point to drive the Chevy at least once a week.