No, that’s not a replica, Porsche 917s really were that tiny.
To put things in perspective, the Porsche 914 had roughly the same dimensions as the original Mazda Miata (OK, the 914 was two inches longer – I said roughly the same). Compared to the diminutive 914, the fire breathing, pushing-1,000-horsepower-chariot-of-the-gods Porsche 917 looks like a kids pedal car. It took huevos mas grande to drive this thing down the Mulsanne Straight at speeds approaching 200 mph.
Source: Jalopnik