His foot began to shake as he pressed it on the clutch - the first sign he was developing the degenerative brain condition Parkinson's disease and the beginning of a very long journey.
Last year, 12 years since he noticed that tremor, he was
in his car once again and
needed to brake - but the
vehicle shot forward when he lowered his foot. He had hit the accelerator instead.
No-one was hurt, but he parked, never to drive again.
Mr Ross, 65 from Glasgow, says: "I think one foot is pushing down, and in fact the other foot is pushing down. The same goes for my hands.
"Later on last year, the
hands started to lose any proper sense of feeling. I have trouble picking things up. I cannot
write any more. I was a civil servant for 20 years, I spent
my whole time writing, I just cannot now."
While he sits talking in his wheelchair his legs jitter and shuffle almost continuously. But it is sudden jerking movements, called dyskinesias, which he finds most unpleasant.
At the moment taking drugs every two-and-a-half hours keeps this under reasonable control, but he has seen this affliction at a more extreme level, causing the arms to fling repeatedly. "That kind of frightens me," he says.
There is pain. "Often with it you get muscle cramps, a cramp in your shoulder. It is very painful," he says. But this is not what scares him.
"Your ability to concentrate on anything just disappears," he explains. "It beats me."
Parkinson's is incurable, but it is not fatal and sufferers can have a normal, or near normal life expectancy. Some respond better to treatment than others and Mr Ross's sudden deterioration last year is unusual.
It was in discussion with a good friend that he decided to take legal action that would allow him assistance with suicide should he wish to die.
He had been a member of Scottish campaign group Friends at the End (Fate) - which supports assisted dying - in the past, although at the time of his decision his fees had lapsed.
He discussed it with Fate and then, he says, when his four children were all gathered together for his 65th birthday, he told them his plan. There were tears, some reservations, one of his daughters made a cup of tea.
As he describes the scene he is lighthearted. He often jokes and laughs as he chats. There have been low moments. Last year when he began to feel as though his feet were planted in two rowing boats, both rocking at different rates, his youngest son came to stay with him. Walking was so difficult Mr Ross needed his help to reach the toilet at night. "I was lying in bed thinking 'I can't go on like this'," he recalls. But almost to his own surprise, he's found he can accept the new limitations on his life - inhabiting one room, relying on a wheelchair. Visits from his many good, nearby friends, and his family keep his spirits up.
He says he wants to know suicide is possible if "things get very bad."
He watched the documentary in which fantasy novelist Terry Pratchett travelled with 71-year-old millionaire Peter Smedley - a sufferer of motor neurone disease - to the Dignitas clinic in Switzerland where foreigners can obtain an assisted suicide under Swiss law and found the setting anodyne and depressing.
He says he wants to die where he was born and brought-up - in Glasgow. In his opinion people take the decision to end their lives too early, either at Dignitas or by their own hand because they do not want to reach a stage where these means are impossible.
Not all those who help someone to die should be immune from prosecution, he says, noting there will be occasions when the police should take an interest "such as when Granny has £10m in the bank".
But he adds: "If someone
helps me with suicide at some point they are not doing it for any gain. They are obviously doing it out of care. That certainly should not be grounds for prosecution."