I haven't seen a bunch of the other replies, but let me speak on this. Endurance Races should be at least as long as an hour (I even envision a beginner-oriented 30 or 40 minute endurance, just if you can't afford any serious muscle), but no more than 2 hours 15 minutes. And can the 24+ hour races without pausing or whatever. Like I've said. Be realistic about endurances. No one person can endure endless racing unless that person has absolutely no life or no interest in television. Races don't need to be longer than they are supposed to be. The reason why I'm objecting all of this is because you have to remember. This game is more of a sim-arcade mix. Do you spend countless hours in an arcade room racing for a long period of time unless in an endurance race? Do you spend countless hours playing a game until it's finished? And I'm talking about getting to the system, and not stopping. Keeping the system on and playing non-stop until the damn thing ends. I've never done that. I raced Tokyo R246 in GT3 for 2 hours, 45 minutes approx. If I wanted to race that long, I'd race in the American Le Mans Series. I don't think it makes you any less of a person to run shorter endurances. It just means that as an arcade racer with an eye for simulation, you have something more feasible.
What would be a nice diversion, however, would be driver changes. I mean, what's an endurance without driver changes? And if you want to employ ANY endurance, do yourself a favor and include Save Games. Treat endurances like championships. Save along the way. I say that after you cross a finish line for a certain number of laps (Like maybe every 10, 20, ot 25 percent of the race), the game will auto-pause and ask if you want to save the endurance. This way, if you DON'T have the time to complete a big race, you can complete it sometime down the road. Feasability. That's what it's all about.
after that, id be like 
then id be like 
because id feel special for doing that. id then 
