for a discussion of the history of the model. (You can skip the early messages until you come to GBK's post because they are full of misinformation that GBK clears up.)
The K-prefix has been used for years for the E13 -- and that is apparently what the Limite actually is. It is not an R13, nor was it based on the R13. As Vytas points out, it is basically an intermediate model.
BTW, unless it has changed recently (yet again), the current serial number list does not take prefixes.