I got a ton of notifications through the app and I actually did the "opt-in" on it. The first guarantee claims $18/hr in fares during certain time blocks on Saturday and Sunday. The other claims $216 in guaranteed fares during these times on Saturday and Sunday... the fine print at the end is, this is before Uber takes their cut on the fares. And to qualify, 51%+ of your fates for the day have to originate from Newton, 80% acceptance rate, etc. So after Uber's take for two days you are "guaranteed" around $140 if you want to hang in Newton and do some potentially painful drives. Get a fare from Newton to Altoona? Great... good luck getting one from Altoona back to Newton.
I actually live in Newton between the hotels and the Speedway. I went online yesterday (Saturday) for 2 hours while I was home during this "prime time"... Not a single ping. I did it one day about two weeks ago out of curiousity and actually did get a ping from a stranded traveler who happened to pull off in Newton and needed a ride to a hotel... so I know it's not a boundary issue.
So Uber is asking drivers to hang out in Newton and promising ~$140 take-home over two days, with requirements. No pings during the supposed peak hours. I drove to Des Moines instead on Saturday and cleared just over $273 in fares and tips, take-home just over $212... for one day, less the 3/4 tank of gas I burnt (gas includes the 70-mile round-trip to Des Moines and back home).
So yeah, I'm ignoring the Newton promise for obvious reasons stated above.
You were probably closer than I was. I know there is some demand after races, but as a whole, Newton is too limited of a market right now to sustain Uber, since no one else in Newton really uses it. The last ping I got in Newton was from a woman who was driving from Chicago whose car just happen to break down while driving through Newton on 80.