That reminds me of that stupid sketch on Saturday Night Live, "The Californians". A fake soap opera about people from LA and the surfer accent, always giving driving directions.
And yes, that's how I'd give those directions too... "Take the 405 from LAX up to the 10, then take the PCH to Malibu."
I was thinking about this the other day: Everyone refers to Los Angeles Int'l Airport as LAX. I can't think of another airport in the United States that is commonly referred to by its airport code. The name "LAX" is even prominently featured with block letters outside the airport.
People sometimes say DCA when talking about the national airport back in DC.
And there's BWI (Baltimore-Washington International).