Yes I've worked quite closely with one. I had to redesign one here to fit a bigger radiator, and to improve cooling efficiency as unfortunately the stock ones aren't very conducive to getting air to flow through the radiator. They are an interesting design though, and they actually serve 3 functions. They are a crash box, a radiator shroud, and a support for the front bodywork, all in one neat little unit. Pig heavy for what they are, as is the entire Lotus package. 

Yeah, I have a VX220 which has the same crash structure.  I've looked at some vanes for the centre 'box' part to help flow for the rad but done very little with it so far.

You have to engineer such a structure from 2 perspectives. IN the roll over situation, deformation needs to be limited to protect the occupants.  An element of energy absorption is also needed.

THe crash structure on an elise is mostly bothered with the later.  It works by absorbing energy through its own destruction. It is entirely outside of the "safety cell" so it doesnt really matter if the structure is destroyed in the process.

A roll structure has the difficult job of both roles. Primarily energy absorbtion is sacrificed for sheer strength to protect the safety cell, but some absorption is necessary.

There is no reason why a composite roll over protection system isn't doable. As proven in F1 and certain other high level motorsport, it is possible with the research and development.

Problem of that is the cost and man hours to get it right.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant