You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature may not be available in some browsers.
It appears that the most current IRS Form 8936 (2012) tells you to limit the credit to $2500 per vehicle, see line 17 below:
Tesla says the credit is $7500. Which is it?