While you and I can clearly see that each simulation and access into 'data' is independent, unfortunately PARFOR doesn't understand the way you've written things. In general, output variables in PARFOR must be indexed using the loop variable and constant terms only. I would suggest that you should be able to flatten your multiply-nest loop, and then it will be simple to get PARFOR to understand.
The key to flattening in this case is to use MATLAB's IND2SUB which can be used to convert a single counter into a series of subscripts. So, you need something like this
% simSpace is the size of the space you're exploring
simSpace = [leng, leng, leng, leng, leng];
% calculate the total number of simulations
numSims = prod(simSpace);
% pre-allocate data
data = zeros(numSims,N+1);
parfor idx = 1:numSims
% convert scalar index into subscripts
[i, j, k, l, m] = ind2sub(simSpace, idx);
% Index input vector (you should be able to use a single vector
% subscript here, as shown)
inVec = brakeRange([i, j, k, l, m]);
simOut = ...;
data(idx, :) = ...;
end
