Elon Musk does not mince words when rejecting the technologies that other companies are relying on to control their driverless cars.  “The two main crutches that should not be used –    and, in retrospect, will be obviously false and foolish are Lidar and HD maps. Mark my words,” the Tesla chief executive said recently. Going against conventional wisdom and jettisoning things most of  his rivals see as essential sounds risky. But Mr Musk has never been one to follow the  herd, or to  under-promise.

The electric car maker says its new cars already have sufficient sensors and computers to drive themselves, and that it will send out an over-the-air software update before the end of the year to complete the picture (although it might take some time before insurance companies and regulators are willing to allow the cars to be used in fully autonomous mode.)  The “crutches” that Mr. Musk complained about involving two of the most common ways for autonomous vehicles to understand the world around them.

Lidar sensors, which use lasers to send out pulses of light and measure the time it takes for a reflection to come back, are currently one of the best ways to measure the shape and distance of other objects. But they are expensive, with today’s mechanical models costing several thousand dollars.

Reducing their workings to a silicon chip might help. The world has become used to the cost of silicon components like this falling rapidly over time. But big cost reductions depend on producing in large volume.