We have become used to Moore's law, originally advanced by Dell's Gordon E Moore way back in 1965, which says that computing power roughly doubles every 18 months. It was a remarkable prediction but it has held firm for 50-odd years.

Cars, however, have not adhered to Moore's law, and by that token should have been steadily stagnating since Henry Ford created the Model T. In what may be an apocryphal story, Bill Gates once
compared cars with computing by saying, "If GM had kept up with the technology like the computer industry has, we would all be driving $25 cars that got 1,000 miles to the gallon." (General Motors wittily replied that if the car industry designed cars like Microsoft, then your car would crash twice a day and the airbag would ask "are you sure?" before deploying.)

But Gates (if he ever really made the remark) was wrong, and the car has far from stagnated. It may not be advancing at the pace of the computer industry, but the cars we drive today are vastly more sophisticated and clever than they were a decade ago – and that's precisely because Moore's law has allowed for ever more sophisticated computers to design, engineer and build those cars, and control their engines and electrical systems when
they're in use. To see just how far things have come, we've compared a 2013 Ford Fiesta with its 2003 equivalent, many thousands of which are still in service on our roads.

ENGINE
This is probably where the biggest advances have been made in the past decade, and much of the advancement has come about because of the pressure brought on car makers to build cars that are ever more environmentally efficient. Back in 2003, the basic Ford Fiesta used a 1.3-litre, four-cylinder petrol engine that could date its ancestry back to the 1968 Ford Escort.

With valves operated by push-rods and an iron block, it was hardly cutting-edge, and that was reflected in its performance. It took a leisurely 18 seconds to sprint (if that’s quite the word) from 0-100km/h and returned a claimed average fuel economy of 45mpg. The most shocking part is the CO2 emissions: 147g/km, a figure that would put the 2003 Fiesta into Tax Band C today, costing €390 a year in motor tax.

By contrast, the latest Fiesta uses an entirely new three-cylinder EcoBoost engine, the most affordable version, with 65bhp that lops a whole two seconds off the 0-100km/h sprint and returns a claimed 66mpg overall. And the emissions figure? A tiny 99g/km, meaning you’ll pay just €180 a year in motor tax. That’s helped by a kerb weight figure that has crept up by just 25kg in a decade – impressive given how much safer and more substantial the new Fiesta is compared to the old one.

SAFETY
You would assume that this is where the biggest improvements have been made over the past decade, but that's actually not quite the case. Looking back at the EuroNCAP crash test data for the 2003 Fiesta, we see a car with a four-star safety rating (not bad at a time when only a handful of cars had reached the full five-star stan dard), with the NCAP testers commenting that the Fiesta "protected well in all areas". Hardly unsafe, then.

Fast-forward to today’s Fiesta and, like almost every other car in its class, it’s a five-star NCAP car , and its pedestrian impact rating has jumped from a poor two stars in 2003 to a healthy 65 per cent score (the NCAP system was changed a few years ago to give more detail in the individual scores). Of course, the biggest advancement since 2003 is in not having an accident in the first place.

The new Fiesta comes with electronic stability control as standard, compared with the 2003 model which couldn’t be had with it for love nor money – although it did at least have driver and passenger airbags and ABS brakes as standard. The new one can even be ordered with a radar-based city braking system (which costs from €320) that slams on the anchors to stop you having a low-speed shunt.

Certainly, it's in safety
terms that the Fiesta has seen its biggest changes, reckons Eddie Murphy, MD of Ford Ireland .

"What we see now as elementary safety technology such as multiple airbags,
which were the preserve of bigger cars 10 years ago, have only now become standard in small cars," says Murphy. " I think ESP has been a major addition to the standard armoury of small cars in recent years. Generally, the affordability of electronic systems has meant smaller cars can now boast spec levels on a par with larger models."

ELECTRONICS
This is where Moore's Law truly comes into play to make the current Fiesta so much more sophisticated a car than its 2003 ancestor. It's not just in the cabin, although the clever SYNC stereo system that connects to your Bluetooth phone and can stream audio tracks, read your text messages and call the emergency services if you
have a crash would have seemed like sci-fi to buyers of the 2003 model. It's also in the engine bay, and it's in large part thanks to the clever engine management system that the new Fiesta gives the old such a thrashing in CO2 terms.

The 2003 Fiesta was a decent car – spacious, fun to drive and reasonably safe. But looking at it alongside its 2013 descendant shows that we may just have to come up with a motoring equivalent of Moore’s law.

Twice as good every decade seems about right.

Let’s go back even further to the 1993 Ford Fiesta - it’s an oldie but is it a goodie?

Going back another decade shows up a vast gulf between Fiestas in just about every area. Safety was laughable back then compared to now. ABS was an option, airbags unheard-of, and ESP was only for the likes of a Merc S-Class. The wheezy 1.1-litre engine was barely adequate (it also dated back to the 1968 Escort) and the hard, plasticy cabin was not a good place to spend time in. It was part of an era when Ford (and so many other car makers) flogged mediocre machinery on the back of clever marketing.

Thankfully, in 1993, Ford turned a significant corner with the brilliant original Mondeo, and the Fiesta was eventually updated and converted into a genuinely sharp, fun-to-drive car which was safe enough to score at least a three-star NCAP crash test rating. It also ushered in the brilliant little Yamaha- developed 1.25-litre petrol engine, which is still in service today. But that basic 1993 car was pretty rubbish, really.

Then again, at the time, did we know any better?