Sat navs - helpful in theory, but they're a lot safer on your kitchen shelf.

"IN 200 metres, turn right."

This is brilliant. I've driven along this road at least 700 times before and taken this turning nearly as often, but I've never been told to do it by a robot before.

"In 100 metres, turn right."

I don't know why I'm using a sat nav. The trip to work, and indeed the trip back again, is so firmly burned into my mind that my children will be born with it hard-wired into their DNA. I have less use for satellite guidance on my daily commute than a snake has for a top hat. Hold that thought, it's more entertaining than I expected.

"Turn right."

Anyway, I don't care. I only bought it the other week and it's still a huge novelty.

"You have arrived."

Thank you, robot. You have correctly relayed my journey status to me and I am satisfied with your performance. I shall reward you by putting you inside a carry case and removing you from the vehicle so that nobody breaks in. See you in eight-and-a-half "I reached the ring road with little understanding of how I had got there and, worse still, an extremely vague idea of how Henry IV became King of England"hours.

The technology of sat navs fascinates and frightens me in equal measure. Instead of using a map in my boot, which I consult when I'm exceptionally lost, I am entrusting my navigation to a spaceship which ascertains my whereabouts, then contrasts that with my destination and pipes the relevant directional data to a small plastic cuboid in my car. Said cuboid then barks precise instructions to me at every junction, while the spaceship continually monitors my progress from its orbital position miles above the Earth.

How is that even remotely normal? When did we become this advanced? If you'd suggested anything like this back in the 1800s, they'd have thrown you in the stocks and confiscated your family. They'd have put you in a sack full of rats and flung you off a cliff. And if you still hadn't had enough, they'd have locked you in a room with a snake in a top hat.

It's lucky I live in the modern day, because I've been coveting sat navs for years. In my mind they still cost £200 and belong in the posh cars of successful businessmen who drive around all day. More fool me. Turns out you can now pick one up for £45 on the internet.

This raises questions, because £45 seems a bit cheap for a robot map from space. I'd probably open the box to discover a Speak n Spell wired up to a compass, connected to a wooden satellite via string. Which, thinking about it, would definitely be worth the money.

So I bought one and, brilliantly, all the things that are supposed to go wrong with sat navs happened on the very first day. I entrusted a familiar journey to York to the device, following the instructions to the letter in the interests of experimental purity, and wound up driving down a residential street towards a brick wall.

Meanwhile, a brief drive through the city to an unfamiliar Chinese takeaway took three times as long as it needed to, after missing a turning and faithfully following the sat nav's amended route plans through a convoluted estate with roads too small to register on the digital map.

And I almost met my match as I tried to multitask on the return trip, trundling through the centre of York at 11pm while the audiobook of Simon Schama's History of Britain fought for my attention with the irregular outbursts of my new navigational robot.

"The Richard portrayed by Shakespeare's quill is perhaps an unfair representation, for the boy was handed the adulation of a country at a remarkably young IN 300 METRES KEEP TO THE LEFT." I reached the ring road with little understanding of how I had got there and, worse still, an extremely vague idea of how Henry IV became King of England. I think he won the throne in a bet.

The trick, I've discovered, is to just use the sat nav for journeys you already know so you can feel futuristic and smug without getting lost. Unless you're listening to an audiobook, in which case it's best to leave it on the kitchen shelf, next to the mangoes. That's what I do.