In honour of my buying a car, here's a breakdown of the Holmes family's (plus James) driving behaviours:
(Forgive my British understanding of driving rules - it is because I am British)
Mycroft - Drives so carefully it's actually embarrassing. He always indicates, is always 5 miles under the speed limit, gives way to everyone and forbids any music or loud talking. His driving is so boring it lulls people to sleep - in fact Sherlock will often join one of Mycroft's drives just to have a nap in the back seat. Incredibly, Mycroft is the one that gets pulled over by the cops the most - he drives so legally, they're convinced he's up to something illegal.
Sherlock - He'd be the most unnervingly accurate driver the world has ever seen if he could keep his attention on the road for more than 10 minutes. Inevitably he starts deducing the people in the cars nearby and forgets he's meant to be driving. He has caused multiple crashes because of this, and has run over at least three squirrels. But no one can parallel park like Sherlock can parallel park.
James - Drives like all the hounds of Hell are after him. If someone tells him to slow down, he just speeds up. He considers anything less than 60mph to be an insult to the car and to the concept of driving in general. Despite this, he is an accurate driver and has actually caused less crashes than Sherlock. There's absolutely no way he would stop and swap details after a collision though.
Beatrice - Drives the car with deadly accuracy, loud metal music blaring as she talks on her phone, fixes her makeup and executes a perfect three point turn all at the same time. She has an epic case of road rage though - God help you if you try to cut her off, because she will hunt you down and she will not be merciful.
Cordelia - Gets even more distracted than Sherlock, usually by something adorable like baby lambs in a field, but this is worse because she has no concept of what a speed limit is. She always manages to somehow charm her way out of a speeding ticket though. James is banned from being in the car when Cordelia drives - he just encourages her.
Silas - He drives with a complete lack of care for others on the road and believes he has right of way always. If anyone tries to remonstrate with him, he will somehow convince them that it was they who did the wrong thing. He will sometimes get distracted if he's mansplaining something to his passenger.
Mrs Crowle - Drives with ten guns in the passenger seat and if someone refuses to let her join the main road, she will fire out of the window indiscriminately. The cops are too scared of her to bring her in.