Alfieri Maserati at the wheel of what is probably a 1925 Diatto Tipo 30 8C (8 cylinders).  He was engineer at Diatto in Torino 1922 to 1926 and had made the 2-litre engine for Diatto. One caption (<a rel="nofollow" class="external text" href="http://www.diatto.com/EN/pagine/maserati_sint.html">diatto.com</a>) says this is at the 1925 GP d'Italia (at Monza on 6 September 1925<a class="external autonumber" href="https://en.wikipedia.org/wiki/1925_Italian_Grand_Prix">[1]</a>), another says this is Monza on 14 June 1925, which would be Coppa del Re<a rel="nofollow" class="external autonumber" href="https://www.racingsportscars.com/race/Monza-1925-06-14-8119.html">[2]</a>; and that these are the "Maserati Brothers", so the passenger (co-driver) may be Bindo, Ettore (or Ernesto). It has the Diatto label on the radiator, so it is not the first Maserati Tipo 26 (yet). But it may be the prototype.
Unknown photographer
<a rel="nofollow" class="external text" href="http://aonclassiccar.fr/wp-content/uploads/2015/07/DIATTO-Tipo-30_8C-1925.jpg">Diatto Tipo 30 8C 1925</a>