Brad Pitt holds his son Maddox
08/07/2008 at 08:00 AM EDT
One is 7, and the other's 44, but together they share ... a need for speed.
And that explains why, for his seventh birthday on Tuesday, Maddox Jolie-Pitt and his father, Brad Pitt
, spent a guys' day out behind the wheel, pursuing one another around a go-kart track in the South of France.
The two have demonstrated their love of wheels before – competing with radio-command cars, racing various bikes and visiting Formula One races. Only, this time, it was their feet on the cart pedals.
"It was just Maddox and Brad," says a source. "Just father-son time." And even though Brad stripped down to don his racing leathers, according to the source, it was Maddox who crossed finish line first.
The outing for dad and his eldest came just over three weeks after the birth
of Maddox's new twin siblings, Vivienne and Knox.
As the guys sped around the track, the rest of the Jolie-Pitts, including mother Angelina Jolie
(whose 2002 adoption of Maddox
from Cambodia helped launch the celebrated clan), remained at the family's home
, Chateau Miraval.