For most people, an automobile represents the second largest purchase they will ever make. As tired a cliche as that may be, it is nonetheless true and makes sense to protect this investment through proper maintenance:
1) Regular oil changes not only increase your engine's lifespan, they lower emissions. At 10,000 km (6,000 mi), convert your engine to synthetics.
2) Prevent corrosion by undercoating your automobile. Twice a year is ideal, but doing it every spring will retard rust and corrosion.
3) Proper tire pressure improves fuel consumption. Tire rotation increases the life of your tires.
4) Have your brakes inspected regularly.
5) Retain and properly store ALL your service receipts.