Key to making any broadcast like this work would be doing the homework ahead of time on the production end - the producers job. I think a really compelling audio netcast could be done with a small team of folks collecting information (Name, class, info on the vehicle, anecdotes, what record they're running against) and recording short interviews with the folks in line that can be used just prior to their runs.
Sometimes, it is tough to get people to say more than, "yes,sir", and "no,sir" on the radio, but a good producer will get folks to open up. The first question should always be, "Can you spare two minutes? If it's okay with you, we'd like to find out about your team" - that will show your respect for their time, and also acknowledge the effort of everyone else around them. And by saying "two minutes", you've let them know that you're not going to be an overbearing pest.
And when all else fails, try, "So, tell us about the car".
If you find somebody during this process who is really good, or is really funny, invite them to stop by for a live interview later, time permitting.
You take the tapes (files) back to the trailer/tent/truck/van, do a quickie edit, and you've got a bunch of fifteen to twenty second bites of the driver telling you about - whatever - and by the time they're at the 3/4 mile mark, where most of the tension is building - you cut back to your on-air guy. The producer would be putting these together, starting early, maybe even doing phone interviews weeks before, coordinating them, and stacking them up for broadcast. And saving some for next month - that's a leg up for the next broadcast, and gives you breathing space if there's down-time.
Live, cut, prerecorded, cut, live, cut, boom, boom, boom, AND you could do build-ups to anything really unusual and cool, (the Electrobike last November comes to mind).
Prerecorded interviews with board members, club presidents, celebrities, racers, a guest former racer as a color commentator - that could fill the dead air if the wind comes up. Ongoing club standings throughout the day, (always subject to verification) would be cool. There's a lot going on, and that can be effectively portrayed with a little planning.
You do a few of 'em right, and you could pick up some sponsorships. Probably not enough to defray the whole cost, but maybe enough to pay for the gas to get the crew out there.
I think Elmo could be paced on radio in a way that would rival a well broadcast baseball game. The timing of the event is such that a well organized producer with a small, informed crew could put together a broadcast that could be really compelling.