Just to add on to your post: With accessories (how most engine weight figures floating around on the web are determined) the VQ35 weighs in at ~420lbs, the L67 at ~470, and the L36 at ~445 from what I've been able to piece together from the web. I think that Doug McGill was asking about the weight of the G6, though, not the weights of the various engines. The G6 weighs in at 3420lbs according to automotive.com which is fairly heavy for a 200hp mid-sized sedan. However, it does get 22/32 c/h gas mileage (an important number to those who would buy a mid-sized sedan), so it's fuel efficiency is not greatly hindered by its weight.

 

Where did you get those numbers?

According to this link on Autoweek, BMW just published with much fanfare that its next generation 3 liter inline 6 will weigh just 355 pounds and be the lightest car engine of its size in the world.

Is the 3.5 liter VQ lighter?

 

I'm thinking that his numbers are for the longblock of each of the engines, rather than the completed engine including accessories.