I told Meg the other day that I'd take a look at XLR8, a $0.99 entertainment app currently rocking 5-star ratings over at the app store. The app uses a mix of GPS and accelerometer readings to simulate racing car sounds as you drive around town.
What you do is this: You hook up the phone to your car's sound system, you place it in a firm mount, and then you press start and wait for the electronic voice to give you clearance to drive ahead. It then monitors movement to match your driving to vroomy vroomy sounds.
If it worked well and less obviously pandered to in-app sales, this would be a really cute app. The problem is, of course, that it didn't work well, could use much better engineering, requires you to watch how-to videos to use the app in the first place, and spends a lot of time and screen space trying to sell you stuff.
Leaving aside the obnoxious lunges towards your wallet, how did the default (free) car work? Well, it made vroomy vroomy sounds -- so +1 for that.
Unfortunately, those sounds were deeply lagged, especially when matched against my morning stop & go commute. Several seconds out of sync, my car started "idling" a block or so after I had already completed my turn and "vrooming" when I was paused to make another. Plus the noises started to get really irritating just a few minutes into driving -- your mileage may vary on that, however. (See? Car pun!) Update: To be clear, I used a direct wire to my sound system, not Bluetooth, so any lags were not due to transmission delays in that regard.
If you do spring for the app, make sure you have your device secured quite firmly as the app works best when it's working in tandem with the car movements, not jostling around your cup holder.
I honestly think the tech could have been implemented far better and more passively (no one wants to wait for a phone to give them permission to start driving), and the obnoxious upsells could have been scaled back a lot.
I'd say all-in-all, it's just a buck if you'd like to give it a try. There are worse ways to spend a dollar.