Maven war artifact with car extension

I am trying to use Maven to generate an artifact for deploying on Vignette Portal. The packaging is exactly the same as a war artifact but the file should have car extension instead.

Options I've tried and I've not been able to complete.

• Use war plugin and rename the final artifact (keeps adding .war extension)
• Use assembly plugin with zip descriptor (not able to change .zip to .car extension)
• Create a new packaging type as described here (can't use war plugin for .car extension)

Which would be the easiest 'Maven' way to generate the .car file? Could you give me some guidance?

Thank you.