It will take 45 minutes to drive to the airport and 15 minutes to park so that's 45+15 = <<45+15=60>>60 minutes (1 hour)
They need to check in 2 hours early and it will 1 hour to drive there and park so that's 2+1 = <<2+1=3>>3 hours
Their flight leaves at 8:00 pm and it will take 3 hours to drive there and check in so the latest they can leave is 8-3 = <<8-3=5>>5:00 pm
#### 5