There is a lot of caching involved and it looks like the VM writes are not synchronous - they do not wait for the actual disk to be written. Normally nothing can beat the native access, but in a VM the "disk" is actually a sparse file that can be efficiently cached in RAM. I see the same behavior/speeds in my VMs if the virtual disk has a lot of free space and I have a lot of free RAM on the host. The speeds get "down to earth" if you fill up the host's RAM.
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There is a lot of caching involved and it looks like the VM writes are not synchronous - they do not wait for the actual disk to be written. Normally nothing can beat the native access, but in a VM the "disk" is actually a sparse file that can be efficiently cached in RAM. I see the same behavior/speeds in my VMs if the virtual disk has a lot of free space and I have a lot of free RAM on the host. The speeds get "down to earth" if you fill up the host's RAM.