Hi, back to Simutrans after a while (RL issues, really sorry! I swear I'll finish my viaduct soon), I'm trying the latest version of the pak (r812).
LMR Bird is coupled with a tender that doesn't match her top speed - namely, Patentee Tender 55 km/h vs Bird 66 km/h - and there are no cars available that can run as fast as her for her entire life span: the only passenger car available is the LMR 4-wheel, 55km/h too.
I don't know if there are other rail cars planned for the early XIX century, but, even if it's temporary, I suggest to raise the top speed of the tender and the cars, both passengers and mail versions.
Thanks. Fixed now in SVN