After about 30 miles of stop-start driving the road to the west opens up, through the pines of Berkshire, and begins to make fast running across the flinty downs of Wiltshire, a county that lies at the heart of the English imagination.
Mapping expert HERE is launching a Real-Time thatfic service that pulls aggregated data from sensors in Audi, BMW and Mercedes-Benz vehicles that are actually out driving the road, making it the first commercial traffic service of its kind that collects real-time information from vehicles from competing carmakers, according to HERE.
That's where motorcyclists who've been driving the road for years ate lunch and shared their mixed feelings.
We usually get to learn from our mistakes, but not when driving – the road is an exception.
It isn't possible to devote your full attention to driving, the road, things happening around you and the phone buttons at the same time.
It'd have been the kid in the front row with all the answers: "Miss, Miss, Miss, me please…" It monitors the light, the rain, your driving, the road ahead, pedestrians… It's fitted with Pilot Assist which means at up to 80mph it'll do the lot: steering, acceleration, deceleration, braking.
For several years, Toyota Prius hybrids that have been specially adapted by the company's engineers have been driving the roads of California.
Now, he says, he has ended up driving the roads with a loaded Uzi in his lap, peering into the hills for sharpshooters.
It's a relaxing gear change from driving the coastal road.
"You get to Mad River Glen and it's like driving the back roads.
"But often it rips through civilian vehicles driving the same roads".
