Migrate all Compute Engine instances to Preemptible VMs after analyzing their resource requirements and usage patterns to cut costs.

Allocate the least possible vCPUs and memory for all Compute Engine instances and set up autoscaling based on instance uptime to reduce expenses.

Buy committed use contracts for the highest possible vCPUs and memory for every Compute Engine instance, ignoring their specific needs and usage patterns, to ensure the greatest cost efficiency.

Examine the resource needs and usage trends of the Compute Engine instances, then acquire suitable committed use contracts for vCPUs and memory, and implement autoscaling with custom metrics that align with each instance's requirements and usage patterns.