The problem, I think, is that it takes 20 years for someone to become 20 years old and then about five seconds for them to become 80. Certainly I don't feel now, at the age of 60, that time is ticking away.
I feel as if I'm in the sort of wormhole you see in sci-fi films. I have a birthday every minute or so, and I'm well aware that at the next one I shall reach 61 — the age at which my father died.
I still feel 19, though, so it's always a surprise when I jump over a farm gate and, on landing, find that my knees hurt. And there's no getting round the fact that last night I went to bed with a bottle of milk, having put my spectacles in the fridge.
Every day feels the same as the one before, but it isn't. It's worse, because age is quietly and silently nibbling away at my joints and my head. I know I can run a mile and power-slide a Lamborghini and fly an F-15 and play bicycle polo and serve a tennis ball at 100mph, but, actually, I can't do any of those things. Without noticing it I've become a grey, ghostly echo of what I used to be.
And so it goes with cars. I look sometimes on classic car websites and I imagine what fun it would be to have a 1966 Alfa Romeo GTA. Or perhaps a Lancia Fulvia HF. Or a BMW 3.0 CSL. We like to think that cars haven't really come on at all in the past 50 years, so any of these things would simply be an interesting and better-looking alternative to the charisma-free eco-boxes that populate the showrooms today.
But, deep down, we know that cars have come on. Quite apart from the fact they have air- conditioning and satellite navigation and electrically adjustable seats, they are so much more usable than they used to be.
The windscreen wipers are a case in point. In the Seventies they simply didn't work. Sure, they moved backwards and forwards when you pulled the knob, but if you were doing more than 80km/h they would be an inch from the screen. And if you were doing less than 80km/h they would make a god-awful squeaking noise — the sort of sound a ship makes when it scrapes along a concrete dock.
The heater didn't work either, and the steering was usually so heavy at parking speeds that the wheel felt like Thor's hammer.
But it's the refinement that's changed most. Even the most dismal modern car is brilliant at masking imperfections in the road surface, whereas the cars we remember from our youth were appalling. They lurched and shimmied and rattled and creaked and wobbled and conveyed information about grip to the seat of your pants with the same enthusiasm as a bolshie teenager.
All of which brings me on to the subject of today's column. For some reason the "classic" Range Rover is now regarded as desirable. I don't quite understand this, because, unlike an Alfa Romeo GTA or a Lancia Fulvia HF or a BMW 3.0 CSL, it's not glamorous or rare or even very exciting. It's just old, so I can't see why well-cared-for examples are now changing hands for between £50,000 and £100,000 ($98,000 to $195,000).
I seem to be on my own here, though. I have one friend who has God knows how many of the old cars, and he takes great delight in fitting them with engines from other things. He lent me one the other day that had an Aston Martin V12 under the bonnet. And while it was very interesting, I was happy to get back into my modern Range Rover for the drive home.
Another friend has invested in an engineering firm that does a fantastic job of modernising old Jensen Interceptors, and now it's turned its attention to the classic Range Rover, creating what it calls the Chieftain. "Would you try one?" he asked. And before I'd had a chance to think of an excuse, there it was, in my drive.
It looked silly parked next to the 12-year-old version I use on the farm, and titchy compared with the three-year-old example I use for trips to London, and I couldn't really see why on earth I'd want to drive it anywhere. But, out of duty, I did, and then all weekend I drove nothing else.
First things first. The standard Rover V8 is gone, and in its place is a 6.2-litre V8 you might find in the front of a Chevrolet Corvette. It churns out 430 horsepower, which is fired via a General Motors six-speed automatic gearbox into Land Rover's four-wheel-drive system.
The result is hilarious. You put your foot down, and, with the sophistication of a covered wagon falling down a hill, the gearbox drops a cog or two, the rear end squats and you're off on a headlong charge that will cause all your passengers to ask you to "stop doing that".
JIA — Jensen International Automotive, the firm behind it — has done a remarkable job of making everything not fall off. It has changed the chassis, fitted fully independent suspension and uprated the brakes, but there's no getting round the fact that you don't really drive the finished product. You just hang on.
It was completely intoxicating, and I haven't got to the best bit yet. You can, if you want, have flared wheelarches and snazzy paint, but the car I borrowed was Austin Princess beige and, apart from the wheels, looked completely standard. It didn't even sound particularly amazing, even though it had a hand-built stainless-steel exhaust system.
This meant I could draw other road users in and then leave them open-mouthed in disbelief as my ancient old classic roared off like a jet-propelled space hopper. I haven't done that sort of thing for years, and it made me feel, for the first time in a while, young.
I drove my newer Range Rover this morning, and I felt 60 again. It was depressing, and I sort of want the old one back. There's a price to pay for that, however, and it's £176,400 ($345,350). That's a lot if you look at this as a car. But if you look at it as an elixir of youth, it's the bargain of the century.
The Clarksometer: JIA Range Rover Chieftain
• Engine: 6162cc, V8, petrol
• Power: 430bhp @ 5900rpm
• Torque: 424 lb ft @ 4600rpm
• Acceleration: 0-60mph: 5.2sec
• Top speed: 202km/h
• Fuel / CO2: 21mpg / N/a
• Weight: 2,032kg
• Price: £176,400 ($345,350)
• Release date: On sale in the UK now
• Jeremy's rating: ★★★★☆
Head to head : JIA Range Rover Chieftain v Kingsley Re-Engineered 1991 Range Rover Classic
• Price:
Chieftain: £176,400 ($345,350)
Kingsley: £175,000 ($342,625)
• Power:
Chieftain: 430bhp
Kingsley: 280bhp
• Torque:
Chieftain: 424 lb ft
Kingsley: 300 lb ft
• Top speed
Chieftain: 202km/h
Kingsley: 160km/h
Written by: Jeremy Clarkson
© The Times of London