Interesting to see that the autograph of Mendelssohn’s Violin Concerto has the instruction Allegro con fuoco, which was changed for publication to Allegro, Molto Appasionato. A couple of other discrepancies exist such as some extra notes for the soloist and the Prestissimo towards the end of the first movement.
I am hoping that there is a documented source to confirm that the changes were Mendelssohn’s – possibly under the advice of Ferdinand David, for whom the concerto was written.
Nevertheless, these performers have chosen to stick to the original markings in their recording:
http://www.classical-music.com/review/mendelssohn-111
Here they are explaining what they were doing:
https://www.youtube.com/watch?v=pkgtHhj6jf0
If you happen to play this piece, it is worth looking at the advice given by Joseph Joachim (pseudo friend of Liszt) who on a number of occasions performed the work with the composer at the piano. His advice is here:
http://www.violinist.com/discussion/response.cfm?ID=26432
After being initially worried that the printed version we now have is not true to Mendelssohn’s wishes, I think that the revisions were for the better. Even with Daniel Hope aware of the original indication, it is very difficult to evoke a con fuoco sound to the first subject of the work, and Allegro, molto appassionato seems to convey the relentlessness for which Mendelssohn was assumedly looking.
Seems like Ferdinand provided decent advice.