A very big constrution project on the Sunset Blvd. bridge over the 405 has begun, and traffic on the freeway over Sepulveda Pass is supposed to be adversely impacted for a long time. You might check
www.latimes.com for info, or post a question specifically about this. Leaving Burbank at 5 p.m., I'd allow a couple of hours to get to LAX. Then you need to return your rental car, etc. If you can fly into and out of Burbank, I'd do it. It's a small airport and the rental car lots are (or at least were) right next to the terminal. Considering the time it takes to get through LAX, and to the rental car facilities, and then drive to Burbank, you could save time by flying into Bob Hope Airport (Burbank), even without the construction projecte on the 405. You can get from/to BUR by taxi, rental car or, for some locations, Metrolink train (or a combination of modes, by taking Metrolink from the airport to Union Station, then light rail or subway from there).