Kinect Joy Ride heads up a fresh batch of demos available on Xbox Live today.
You can also sample Harmonix's Rock Band 3 and Activision's chopper sim Apache: Air Assault.
You shouldn't need a demo to convince you to open your wallet for Rock Band 3. Johnny Minkley's perfect 10/10 review should be all the impetus you need.
Kinect Joy Ride, on the other hand, only managed 5/10 earlier this week, so you might want to find out what you're letting yourself in for there.
However, the Joy Ride demo also comes built into Kinect Adventures, which is bundled with the hardware, so an Xbox Live release seems rather redundant.
Either way, unless you're an American you'll need to wait to 10th November to try it, when Kinect launches in Europe.