Unless you like to drive even longer in LA traffic (or you really want to hit that McDonalds on Century ) I'd suggest an alternate routing:

1) When you exit the Hertz lot, turn right (onto Arbor Vitae)
2) Take immediate right at the light (onto Airport Blvd going north).
3) Turn right on La Tijera Blvd (intersects at an angle, so now you're travelling NE)
4) La Tijera crosses over the 405, which you can grab going north from the left lane.

In my experience, this is the quickest route to/from the LAX Hertz lot. La Tijera is an exit from the 405 South, so just reverse the above to return...

Or is there construction going on that I'm unaware of? I haven't been in LA since February.

Good luck with the traffic. While not as bad as some east coast spots I can think of (Manhattan, Boston, etc...) driving in LA traffic can be an "unique" experience.

--Brett