Impossible to set two interdependent variables for demonstrative pronoun (Der, Die, Das)

It is not possible to set interdependend variable.
This will set @word always to "Vespa" and @dempron always to "Die"

#random{
#set{@word|Auto}#set{@dempron|Das}|
#set{@word|Bus}#set{@dempron|Der}|
#set{@word|Vespa}#set{@dempron|Die}
}

It is necessary to change "Das Auto" to "dieses Auto" or "dem Auto.
This doesn't work either

#set{#random{Das Auto|Der Bus|Die Vespa}}

Because i can't check if there is "Der", "Die" or "Das" in a variable.

Goal is to make a text like this:
Was sagen sie zu dem Auto? Das Auto ist schön. Deshalb möchte ich dieses Auto kaufen.