It's the car business. Commission sales is always challenging. Some months your up some months your down. You have to plan for the ebb and flow. Work life balance is rough, not because of the Auto Group, but because of the nature of the job.
Your tenure carries no weight. They will fire you without cause or explanation, even after working there for over a decade. Recent GM has no vision or plan for the store, just makes changes for the sake of change and then blames those affected negatively by the unplanned change for the changes failing. This has happened multiple times.