Question about tree shaking vendor packages

hi,

I am trying this template and using the ES2015 webpack config and it appears to be working for app specific code. For example I edit the car.ts file and try adding and removing references to V6Engine class and this causes the file size to go up and down.
However when I try to import D3, it doesn't appear to be tree shaking functions off that module?
Is there anyway to get this to work?