We waited until 10 minutes after the game. Parked in the Orange car park about 50 yards from the EL1 entrance we use. It's £10, but seems secure. We head straight out passed Asda and the Velodrome and chugged up to wards the motorway, which is slow. All said, back in Coventry at 19.20, having left the ground after 17.00 seems outstanding to me. I have left early before, but we found that we missed the odd goal and actually saved maybe 20-30minutes only which is daft given that it is a day out. We looked around for a better parking spot and escape route so that we could stay the whole game.
As others have said, parking away from the ground can work too. The 6th Form College is a 15 minute walk but a quick getaway is almost always assured. I don't fancy the walk as I have a dodgy knee.
If people were slightly more reasonable when jostling to get out of car parks in general, things would be a lot better. I'd also turn off the traffic lights as they just seem to actually generate more problems than they solve.