Professor Martyn Thomas (Letters, 27 November) makes a powerful case for great caution in introducing “driverless” cars. Many manufacturers have replaced the traditional manual handbrake with a switch controlling a powered brake, which depends on both battery power and software. The handbrake was always the last resort when there was no other means of stopping a car. Now that will no longer be available. Of equal concern, if the handbrake software was hacked and switched on while the car was moving fast, it would crash catastrophically. When our new car was being explained to us last year, the salesman said “do not switch on the handbrake when moving except in an extreme emergency; it has no graded response, it is either on or off”. And what happens if the battery goes flat?
Greg Conway
Amersham, Buckinghamshire
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