We have two leaders (co-presidents) of our team for redundancy.
Our leaders are chosen so that one leader is senior (in grade only). This senior leader would have been the junior leader last year, therefore they know (and more importantly can teach) the ropes to the junior leaders. In additions, academic stuff (tests, projects) will usually not affect both leaders at the same time. When we were chosen by last year's dual leaders, they made sure that we could mesh well together. Both of our leaders are equally competent, and so the workload is split.
When someone needs something done, they come to either one of us. If it is something
really important (like event organization or pizza flavor
), we'll ask the other to help decide. Ordering parts, shirts, etc. can be done solo. We avoid confusion by making sure that we are both up to date as stuff happens during builds season, and weekly for the rest of the year.
We also have 3 subgroup leaders. They are the "Directors of ____(programming, mechanical, treasurer)". Because of our team's size, we let the Directors allocate students according to where they are needed. For example, someone who is good with both mechanical and programming will exist in both groups, depending on how many students a task will take.
Having dual leaders is a good system for us, as we haven't had problems with it yet. However, four "quad leaders" would make communication and cohesiveness confusing and difficult to obtain with this system. If your are dead-set on four, I think they would have to specialize.