'Chaos' at scene of Westminster attack but the attack was even more serious than I realised

This BBC report https://www.bbc.co.uk/news/uk-45485404 contains this previously unreported piece of information:

'Police say the attack began at 14:40 when Masood's vehicle, a rented Hyundai Tucson SUV, mounted the kerb on Westminster Bridge, travelling at an average speed of 31mph.'

The driver was exceeding the speed limit? There's no excuse for that, I'm surprised that the police haven't taken him to task for that. After all we all know that "speed kills".