Suppose that I need to run a multivariate linear model Y = X B + E many times with the same model matrix X but each time with different response matrix Y. Is there a function available in 'car' package similar to refit() in lme4 package so that the model matrix X would not be reassembled each time? Also, runtime can be saved without repeatedly performing the same matrix computations such as (X'X)^(-1)X'. Thanks, Gang