CSMA/CD in VLANs query Ethernet is based on CSMA/CD. When using VLANs, the number of stations can become very high, making CSMA/CD inefficient. Are there any mechanisms that VLANs use to overcome this?

VLANs segregate a shared link-layer (L2) topology into smaller broadcast domains.

CSMA/CD is the physical-layer (L1) access method for half-duplex Ethernet, normally only used with repeaters, hubs, or ancient Ethernet variants. Practically, it isn't even supported with current gigabit-and-faster variants any more.

Since VLANs can only (reasonably) be used with switches and switches predominantly use full-duplex links without CSMA/CD, both technologies don't really come into touch with each other.

Of course, you could configure a VLAN trunk to use half duplex on purpose, but why would you do so? Additionally, CSMA/CD would work just as well with or without VLAN tags.