I have a car that I don't need to use often. I only really go the store and pick up groceries in it. That is only about once a week. Is tha
Using it for such short journeys is a very bad idea - the engine won't get warm enough to fully lubricate everything (oil is thicker when cold and doesn't circulate as well), won't charge the battery fully (in fact hardly at all), won't boil off all the condensation from the exhaust etc. You'll destroy the battery in a year or so, and dramatically reduce the life of the engine.
Plus you're paying all the maintenance cost, insurance, taxes etc for just 50 miles a year - You'd be better off selling it and paying the grocery store to deliver your shopping...
I’ve always heard that you should actually worry more about cars that have been sitting still for too long.. Thinking not using a car makes it last longer is the wrong idea.
Things like corrosion don’t stop because you’re not using the car, and riding it is actually beneficial to keep the moving parts freedom of movement and the oil flow inside the engine and transmission. When corrosion happens in the contact area of moving parts, having them working will keep the rust from staying in place and have part of it removed in the oil. If the engine/transmission sits still, larger pieces of rust will concentrate in that area and when the engine is turned on will probably cause more damage.
Using the car often is also good in the sense that you will notice different behaviors easier and be able to fix whatever is wrong. For example, if you use the car everyday it’s easier to identify noises that weren’t there before, because you have a constant reference.
I might be forgetting to mention other benefits. One thing that riding a mile per week will also probably cause is your battery to run out faster.