Modern cars are no mere mechanical devices. They're pervasively monitored and controlled by dozens of computers linked by internal vehicular networks so complex they put your average PC to shame.

So it came as no surprise that very recently, the Jaguar XJ Super Sport we were testing -- one of the most fastest, most thrilling, most technologically advanced cars on the planet -- suffered the dreaded Blue Screen of Death. Fortunately, that was the only kind of crash we experienced.

Usually, hitting the car's power button causes its beefy 503hp supercharged V8 engine to roar into life. On this occasion, the roar was replaced by an eerie silence and absolutely no response from the XJ's entertainment, guidance or instrument systems. Its 8-inch infotainment display and the foot-long computer screen it uses in place of a speedometer were both as dead as a dodo.

Our first instinct was that we'd exhausted the car's battery by watching too much Eminem on its integrated DVD player, so when the friendly Jaguar Assist recovery man arrived an hour after we called, we expected him to slip on some overalls and take a look under the bonnet.

Instead, we were told the problem was far more complex and to get to the root of it he'd need his laptop, some bespoke software and a wireless dongle.

So off he went, connecting one end of a cable to a USB port on his trusty Panasonic CF-18 ToughBook, and the other end to the XJ's OBD-II (On-Board Diagnostics 2) port on the bulkhead beneath the steering wheel. Once hooked up, he tapped a few buttons on the laptop's touchscreen and fired up Jaguar's bespoke vehicle-diagnostics software. The tension, from our perspective, was palpable -- diagnosing crashes in Windows Vista was certainly never this exciting.

Over the minutes that followed, the software analysed every one of the car's digital systems in search of a problem. The culprit could have been any number of things -- the Bosch-supplied, Linux-based infotainment system, the Visteon-supplied virtual instrument display, a heat-ravaged processor, an errant mouse somewhere in one of the car's hundreds of miles of wiring, or the dodgy contents of a CNET UK memory key in one of the XJ's two USB ports.

Like most computer crashes, the true cause couldn't be determined on the scene. Instructions beamed down from Jaguar Towers via the laptop's Wi-Fi dongle suggested further diagnostics were required back at the factory.

We weren't about to let the car go, however. We loved it too much and besides, we had a Car Tech video to finish. As luck would have it, we'd parked somewhere inaccessible by tow truck, so our engineer postponed the factory diagnosis, and attempted a quick reboot to get us back on the road.

Curiously, whatever problem caused the XJ to crash also caused it not to respond to the laptop's reboot command, meaning we had to treat this £90,000 Jag like we do our janky old HP laptop: we disconnected the battery, killed the power and restarted it manually.

It's important to stress that this sort of problem isn't restricted to Jaguar cars -- any automobile that relies on computer hardware and software is at risk of similar crashes.

We need only look as far as Toyota, which issued a software update to alleviate problems with its braking system, or Volvo, which recalled 26,000 cars worldwide due to faulty software that caused engine problems in its T6.

Your car could be next. One recent estimate suggests that the typical luxury saloon now contains over 100MB of binary code spread across 50-70 separate computers, each of which communicates over one or more shared internal networks. Something, somewhere, will inevitably go wrong.

Admittedly, we'd never trade a car's advanced systems to return to the dark ages. Electronic fuel injection, electronically deployed airbags and GPS systems with integrated satellite transmitters are all a part of our modern lives, but this sort of event raises the question: are we becoming too reliant on electronic gadgets?

What do you think? Have you experienced a similar crash? Are you worried about the influx of technology in modern cars? Let us know in the comments below then take a look through our photo gallery above to see how the drama unfolded.

Once the crash occurred, we made a call to Jaguar Assistance, who sent a skilled engineer to the scene in under an hour.
Instead of opening the bonnet, our engineer produced a laptop and fired up a Jaguar diagnostics application.
Jaguar's laptop of choice, in this instance at least, is a Panasonic ToughBook CF-18 with a touch-sensitive display.
At one end of this diagnostics cable is the male end of a USB connector, which is inserted in the laptop. This end connects to the car's OBD-II port.
The ODB-II port is at the top right of this picture above the accelerator pedal.
Once connected, the software identifies the vehicle and runs diagnostic tests on its critical systems.
The Wi-Fi dongle can be used to beam diagnostic info back to Jaguar Assistance HQ.
No faults were found, so Jag Man attempts a system reboot with the laptop.
But that doesn't work, so we do it the old fashioned way -- by disconnecting the battery, waiting a bit, then reconnecting it again.
We're back up and running, which is just as well -- we have an episode of Car Tech to shoot.
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