When the Zion Canyon shuttle is operating, private vehicles are not allowed on the Zion Canyon Scenic Drive beyond the visitor centre except for limited authorized traffic. The shuttle is efficient but lines can be long on summer mornings and holiday weekends.
Bikes and e-bikes are a good alternative for fit visitors, especially if you want to move at your own pace between stops. The east side and Kolob Canyons are driven by private vehicle year-round, subject to weather, closures, and tunnel restrictions for oversized vehicles.