Here are a couple of young gents in a very sporty looking circa 1910 Stoddard Dayton roadster. From studying the size of the car, it appears that this maybe one of the big fifty hp models which were quite good performers and did well in racing. Photo The Old Motor.
Photos from the Horseless Age Magazine below, show an earlier and smaller 1907 engine. You can see clearly the unique overhead pushrod and rocker arm design that they are famous for.