Life is a journey - especially if you're a motor obsessive like Richard Hammond. As his new memoir is published, Hannah Stephenson discovers the presenter's lifelong passion for cars and motorbikes Richard Hammond is like a child in a sweet shop as he relishes the arrival of his brand new white Porsche 911 GT3.

"It's coming at the end of November," squeals the Top Gear presenter known as the 'Hamster'. "I'm so excited. And, yes, I paid full price for it. It cost a lot, I'm embarrassed to say how much." A little research reveals that the starter price is around £100,500.

"I won't sleep the night before it's arriving," he says. "I have a picture of it that I look at regularly. The day I'm not excited about a new car arriving is the day I will give up Top Gear."

The pint-sized presenter and his petrolhead workmates, Jeremy Clarkson and James May, are currently filming the new series of the most successful motoring show ever, to be shown in January.

Hammond, 43, will also be presenting a three-part BBC One series next year called Big Weather, examining (and experiencing) extreme weather.

"I am happier than I've ever been," he reflects, "but I could attribute that to having two beautiful, healthy daughters who are now best friends. I look forward to seeing them when they come home from school."

He's managed to cut back on work this year, which has enabled him to spend more time with his family, wife Mindy and daughters Isabella, 13, and Willow, 10, at their 20-acre plot at Bollitree Castle, nicknamed 'Hamelot', in Herefordshire.

Of course, his lifelong interest in cars and motorbikes - he has around seven or eight cars right now and a staggering 26 motorbikes in his barn - has continued.

"I go and sit among them with a cup of tea sometimes, when life becomes too much," he says wryly.

His love of motors is obviously rubbing off on his family. He now lets Isabella ride on the back of his motorbike, he admits.

"Mindy isn't concerned about that, because she rides horses with Willow, and air ambulances are called out far more frequently to equestrian accidents than they are to motorcycling accidents."

When he was a child, his own parents agreed that they'd let him have a motorbike when he turned 16 - and he never let them forget it.

"When I was five, I worked out how many days it was before I could take my driving test and I realised it was 365 days fewer before I could ride a motorcycle. They should have said no at that point.

"They felt uncomfortable about it, but I'm very grateful to them for letting me have one."

Now he reflects: "It's all about risk assessment and thinking, 'I've done everything to mitigate against things going wrong'. Is it worth doing? Yes, in the face of the risk that if it does go wrong, this is what might happen. But that's like everything in life, from walking out of the front door to boiling an egg."

Of course, he will worry if Isabella wants to get her own motorbike at 16, as he did, but his philosophy is that he hopes he will have raised her with sufficient sense to avoid hurting herself.

But he somehow can't see himself becoming his daughters' driving instructor.

"I don't think they want me to be because I'm just Dad and what do I know about anything?" he laughs. "But I can't wait to go out in a car with them, to have them drive and to teach them."

But is the Hamster a good driver? "Not really. Every time I say I am, I crash. Every time my wife or daughters say, 'Just be careful', I go and do something stupid. I've done a lot of driving so I'm an experienced driver, but that doesn't necessarily make me a good one."

He has recently taken a more sedate journey to write a coming-of-age memoir through his recollections of eight key road journeys in his life, including family trips from Ripon to Harrogate, Solihull to Weston-Super-Mare and Ripon to Penrith. The collection of journeys form his latest memoir, On The Road.

They are all very different trips: the long pilgrimages to Weston-Super-Mare to see his grandparents as a child, arguing in the back seat with his brothers; the crushing disappointment wheeling out the gift of a bike he didn't want and taking it to school; his first car, a 1976 Toyota Corolla Liftback 1600, which he managed to write off before he was 18.

"From about 12 to 14, I was really quite soulful, thoughtful and sensitive, and then the hormones came along and smashed it all up," he says.

"By the time I was 16, I was desperate to ride my first motorbike. The journey may have been humdrum but the bike meant freedom, breaking out and making my way in the world as a growing young adult."

Even today, his hobby is tinkering with cars and bikes. "I run motorcycles going back to the 1920s and rebuild bicycles. I love machinery."

Hammond is no stranger to accidents, his most famous coming in September 2006 when he sustained a serious brain injury while driving a jet-powered dragster for Top Gear on a disused airfield in Yorkshire.

He had reached 314mph - an unofficial British land speed record - before a tyre burst and sent the car spinning out of control.

The following January, he was back at Top Gear. He has said that work probably helped his recovery.

"All of our lives are studded by major events, and they change us," he says. "It might be getting married, getting or losing a job, having children. There are tragic things that happen in everyone's lives and they do change us. Brain injury, in my case, has now been filed away to become one of the major formative events in my life.

"I don't wake up of a morning and think, 'Oh no, I've lost the keys because of my head injury'. I've accepted that we can be changed by so many things and I've just filed it along with them."

But he admits he lives for today more now than he did before the crash.

"I believe that what we have is now, the past doesn't exist any more, but neither does the future. The future only exists in that the anticipation or dread of it can influence your present."

He does sometimes get scared about those high-speed exploits. "If I'm driving a very fast car or attempting a tricky manoeuvre, I do sometimes sit quietly behind the steering wheel for a moment and think. I'd be an idiot if I didn't."

However, he says the highest safety measures are always in place. "We're not gung ho, and I'd never work with a bunch of people who asked me to do something that I wouldn't be prepared to do."

By the time his girls can drive, cars may be very different, he predicts.

"It's a constantly changing landscape. There are electric cars, hybrid cars, hydrogen fuel cell cars coming on, which is great.

"In the next 20 years there will be systems for effectively becoming a train you drive on the motorway, hit the button and your car hooks up and talks to all the other cars around it to maintain distance, and drives itself.

"Speed limits may change, because if you're all hooked up on a motorway there's no reason why you couldn't do 200 miles an hour.

"I think petrol-powered cars will still be around, but they'll be for hobbyists like me."

:: On The Road by Richard Hammond is published by Weidenfeld & Nicolson, priced £18.99. Available now