Alistair Barr:

Google Inc. GOOGL +0.02% caused a stir earlier this year when it unveiled a self-driving car without a steering wheel, or pedals for braking and accelerating.

But Google’s goal of an autonomous car is bumping up against new testing rules from California’s Department of Motor Vehicles.

The rules, which take effect on Sept. 16, require a driver to be able to take “immediate physical control” of a vehicle on public roads if needed. That means the car must have a steering wheel and brake and accelerator pedals, according to Bernard Soriano, the top official developing the rules for the state.

Google could test its fully autonomous prototype on private roads, or try to test the vehicle on public roads outside California.

But the company said it plans to comply with the California rule by building a small, temporary steering-wheel and pedal system that drivers can use during testing.