My top pick is any of the Love Bug movies — there are six in total, from tge one The Love Bug that came out in the late 60's all the way through to Herbie: Fully Loaded that came out in early 2000's, and they're all G-rated except the last one which is PG, so you really can't go wrong with any of them for a birthday. For a younger kid, Herbie Goes Bananas is a great choice because the main character is a kid, making it very relatable. If your son is a bit older, Herbie: Fully Loaded brings a more modern edge, while The Love Bug is the classic Disney crowd pleaser and the highest rated of the bunch.
And if you want something a little different for a change of pace, Back to the Future movies are a fantastic alternative they are PG though, the DeLorean is essentially the star, and it's got a genuinely fun chase sequence that kids love. But honestly, with a whole shelf of Love Bug films to choose from, you're already sorted. Happy birthday to your son! 🎂