On LP, I had days when I would take a break and leave the gym for a few hours and come back to finish the session. That worked better than finishing the session the next day.
Just gotta do what works best for you. If the drive home helps to re-invigorate you, then by all means, keep on doing it
Edit: but the trick I've found for getting through long sessions is to start eating the carbs before the session starts and slowly eat during the session. I eat a few pieces of candy before I start, and slowly eat some more in between sets. Maybe the Gatorade or Cliff bar isn't kicking in quite fast enough if you have it after squat and bench.