Despite this sales success, the 3-series is still seen as being exclusive, and it has the residual value predictions to match. It has ruled the junior executive roost for a long time, but its crown is coming under threat.
Firstly, the new Audi A4 is an excellent car and it was crowned the best premium upper-medium car of the year at the 2002 Fleet News Awards.
Secondly, Jaguar's much-lauded X-type range has been picking up sales thanks to its blend of traditional styling and up-to-date features such as four-wheel drive.
So that staple diet of the junior executive ranks, the entry-level BMW 318i, is facing the toughest test now that Jaguar has launched a 2.0-litre X-type priced below that magic £20,000 barrier.
For £19,995 on-the-road the X-type 2.0 blends traditional Jaguar styling with a price tag that is tantalisingly close for many young execs.
So the price is certainly right for the X-type, but can it offer fleet decision-makers a viable proposition to run over a typical operating cycle?
Well, yes it can. The Jaguar costs 32.65 pence per mile to run over a three-year/60,000-mile operating cycle. It's the most expensive here to run but only fractionally, with the BMW 318i costing 32.53ppm and the Audi A4 leading the pack on 32.17ppm.
The Jaguar's competitive performance is something of a surprise because of its low fuel economy performance.
The X-type records 30.7mpg on the combined economy cycle, outclassed by the Audi (34.4mpg) and dwarfed by the BMW on an excellent 39.2mpg thanks to its adoption of Valvetronic technology.
This means the X-type costs more than 2ppm more than the BMW on fuel costs alone. But the X-type scores well in other areas. CAP Monitor estimates it will retain 44% of its price new after three years and 60,000 miles, just ahead of the BMW (42%) and Audi (41%).
As a result it has the lowest depreciation costs of the trio and it also scores well on servicing, maintenance and repair costs. At 2.54ppm it outclasses the Audi (3.41ppm) and BMW (4.33ppm).
But in this sector, employers may be prepared to pay a little extra to have the car of the moment and the X-type certainly is that.
With so many 3-series in company car parks, the X-type is set to become the young executive's car of choice.
It also costs the least to lease over the three-year/60,000-mile cycle, costing £400 per month compared to the Audi's £411 and BMW's £421.
But the X-type's biggest shortcoming is its carbon dioxide emissions. It pumps out the gas at a rate of 219g/km, qualifying it for far higher benefit-in-kind tax ratings than its two list rivals.
For the first three years of the new system, the X-type will incur a benefit charge of 25%, 27% and 29% of its P11D price respectively. Compare that with the Audi at 21%, 23% and 25% and, even better still, the frugal and clean BMW on 17%, 19% and 21%.
For a 40% taxpayer, the Jaguar will cost £165 a month in benefit-in-kind tax, the BMW just £112.
The Jaguar would win were it not for its very high CO2 emissions. No matter how desirable it is, drivers will think again when they look at how much it will cost them in benefit-in-kind tax, especially when compared to the BMW.
In fleet terms, the Audi wins this test for me. The combination of a perky engine, low running costs, strong image and clean styling make it a winning combination.
In a sector where the 318i is the default choice, the Audi is a car for the more discerning driver. Much as I love the X-type, and as good as it is to drive, it will cost your drivers a small fortune in tax compared with its rivals. But when the diesel-engined X-type arrives, the story could be completely different.
Behind the wheel
THE 2.0-litre entry-level X-type is the second model in this range I have driven, the other being a 2.5-litre version with a four-wheel drive set-up.
The 2.0 model is front-wheel drive and when it was originally announced some parts of the motoring world were up in arms, believing Jaguar's traditional driving standards would be spoiled.
Well, they needn't have worried, because the 2.0 model is better to drive than the 2.5. While the 2.0 may be down on power compared to the 2.5 (157bhp against 194bhp respectively), it doesn't have that four-wheel drive set-up to carry about, meaning weight is saved.
During my week with the 2.0 I found it livelier to drive than the 2.5 and was continually impressed by the way Jaguar's chassis engineers have designed a front-wheel drive car that generates so much grip.
During hard cornering the X-type would remain composed and keep its line, with understeer only coming on when the car was pushed extremely hard. In normal driving conditions, the average driver wouldn't notice if this car was four- or front-wheel drive.
With 157bhp on tap, the X-type 2.0-litre is the most powerful car of our test trio, but the lazy nature of its V6 engine means you don't feel you are travelling that quickly. However, glance down at the speedo and you realise you are comfortably exceeding the legal motorway limit - noise levels have been suppressed superbly in this car and the only sound you can hear is faint tyre roar.
Power really comes in at about 4,500 rpm but the surge is over too quickly as you have to change up at the lowish red-line at about 6,200rpm.
This means you have to use the gearbox a lot and this is where the 2.0 falls down - the shift is too long and the change rather notchy, making quick shifts a difficult thing to master. The problem is not helped by a long travel clutch either.
And while we're in that neck of the woods, the wide transmission tunnel doesn't leave much room for your feet around the pedals. Even my small feet struggled to get comfortable and the tunnel is too narrow to allow you to move your left foot off the clutch comfortably - instead you have to hook your left foot back and then underneath the clutch pedal.
But aside from that the driving position is first rate with comfortable seats that hold you in place firmly and a fully adjustable steering column to ensure the optimum driving position.
THE 2.0-litre X-type is the pick of the range for me (although I haven't driven the 3.0 version), as it combines a smooth engine with a fantastic chassis set-up.
But it doesn't feel as quick as its 157bhp thanks to its lazy V6 engine and awkward gearbox and clutch action. But that will be the appeal for some - effortless performance and that traditional Jaguar styling. The Audi feels the quickest of our trio, thanks to its turbocharged engine's more lively power delivery while the BMW's chassis never ceases to impress.
But as a compromise of all three, the Jaguar would edge it for me, just ahead of the Audi.