Backstory: Owning your car is a thing of the past. Uber, Lyft, Dockless Bikes, Bird, Lime, etc are popping up in every major city. With so many apps, the choices are becoming overwhelming.
The Idea: An app that aggregates all ride sharing and rentable means of transportation.
Deep Dive: You would tap into every possible ride sharing and rentable transportation option. Give all the options you would present options to the user with the fastest time to arrival and cheapest option.
Often times scooters are a few blocks away but an uber may be 10 minutes out. Given traffic, the scooter may be the fastest option.
Another factor to consider is the weather. Last weekend Julia made the last minute decision to uber instead of taking a bird and five minutes into the uber, it started to pour. It was definitely the best choice.. don't tell her that ;)
Validation: I would love to see a true comparison of time until uber pickup/drop off vs scooter or even walking. There are already scooter aggregate apps popping up, taking all options into consideration would be a sensible next step.
Monetization: As you're aggregating multiple services you should run ads to monetize. You could sell premium spots to the different ride sharing/scooter companies.