The fastest man-made object ever

With a peak up to 252 792 km/h in solar perihelion, April 17, 1976, the Helios probe is the fastest man-made object of all time. This incredible speed is largely due to the interaction with the sun : Helios II rose to just under 43.44 million kilometers from the sun (this is the object that approached the sun the most without being destroyed), taking advantage of solar attraction to increase its speed. 

The probe has exceeded the orbit of Mercury, and although it is no longer sending data since 1985, it is still in orbit around the sun.