Motor racing isn't everyone's cup of tea, but - in its various forms - it's undeniably a big sport.

For Australian fans of four-wheel racing the big two are, on the national scene, the V8 Supercar Championship and, on the international stage, Formula One.

The pedigree open-wheelers from overseas and the Holden and Ford sedans come together on the same program at next week's Australian Grand Prix in Melbourne.

So just how big are they in terms of popularity?

Well, just as the fumes at racetracks intoxicate the petrol-head fans, so it seems they play havoc with the arithmetic of the promoters of motor sport.

V8 Supercars Australia (V8SA), at its early February launch in Sydney, where it unveiled an advertisement featuring Pink with some of its star drivers, boasted that its championship last year attracted, over three or four days a round, "event attendances from 50,000 people in Darwin to around 300,000 in Adelaide".

Note firstly that, unlike the crowds for major ball sports, these numbers are neatly rounded off.

Despite all the technology in motor sport, its organisers haven't developed - perhaps haven't wanted to develop - turnstiles to produce accurate attendances.

V8SA conveniently forgot to include in its launch crowd mention that a round of its championship at Victoria's Phillip Island last November - admittedly the second there in just a few weeks, due to the cancellation of an overseas round - drew little more than 15,000 spectators for the weekend.

And the WA Sporting Car Club says the attendance at the Perth round last year at the Wanneroo or Barbagallo circuit was 32,500. WA has recently been dropped from this year's calendar, but that's another story.

So there were at least two rounds below Darwin's supposed 50,000 - and last year there weren't any rounds in the Middle East.

At the Abu Dhabi and Bahrain rounds last month that controversially preceded last weekend's Clipsal 500 in Adelaide there were almost more competitors on the track than people in the grandstands.

V8SA ringleader Tony Cochrane, who thinks this author too pessimistic, is quick to spout that his category has a new TV deal with ESPN Star in Asia giving it - he claims - access to 359 million viewers.

And another recent deal, with SpeedTV in the US, supposedly gives it entrée to 79 million in the Americas - north and south.

Just don't expect any actual audience figures, as opposed to potential reach, on V8 Supercar telecasts in those parts of the world, because they inevitably will be a miniscule fraction of those millions.

In Britain, for example, where V8 Supercar highlight packages are shown on subscription Motors TV, the audience is consistently less than 10,000 viewers, compared with an average of almost 4 million on free-to-air BBC for F1 grands prix.

Even at home the V8 Supercar TV picture is less than rosy.

Sure, crowds at the tracks are generally pretty good (277,800 announced for the Adelaide event just gone, including 89,600 on Sunday) and there is a sizeable body of viewers following on TV, but in the main the number of viewers on the Seven Network is shrinking, even for Bathurst's Great Race.

Adelaide is V8SA's hallmark metropolitan street event, yet the average TV audience in the five major capital cities was 338,000 last Saturday and 476,000 on Sunday - a two-day total of 814,000.

That was its worst total in five years - down 27.8 per cent on last year's 1.128 million, and an even bigger 34.8 per cent below 2007's 1.250 million.

The bottom line on V8 Supercars is that the propaganda doesn't tally with the realities.

It's a similar story with F1.

Attendances for the four days of Melbourne's GP are consistently announced at around 300,000 these days.

Yet the number of grandstands and corporate facilities at the temporary Albert Park venue has shriveled in recent years without any sign of a corresponding increase in spectators in the cheaper general admission areas.

A joke within the Australian Grand Prix Corporation in my eight years there as media manager was that chairman Ron Walker (pictured, above) could tell you what the crowd was (going to be) in advance!

For years, all F1 GPs around the world were thought to have a global audience of hundreds of millions - behind only the Olympics and soccer World Cup, we were told, and they only come around every four years, while there are 16, 17, 18 and now 19 GPs a year.

The hundreds of millions sounded suss, but if anyone had contrary evidence it wasn't sighted in those days.

Now the truth is starting to peep through.

Initiative futures sport + entertainment, a London research firm that is part of the Interpublic group, specialises in analysis of sports telecasts.

It found America's Superbowl to be consistently the most watched sports event in the world in years outside of Olympics and football world cups, although last year the Superbowl, still overwhelmingly of American interest, was topped by the UEFA Champions League final (with 109 million live viewers versus the Superbowl's 106 million).

Initiative also found Brazil's GP at Sao Paulo's Interlagos to be the most watched F1 race in 2006, '07 and '08 - when it was the world title-deciding final round and in a timezone tailor-made for the key European markets.

Initiative analyst Kevin Alavy says that those Interlagos races were watched live by about 85 million, 82 million and 78 million viewers respectively.

Last season the final GP was at the new billion-dollar Abu Dhabi track, although the title was decided - in Jenson Button's favor - a couple of weeks earlier in Brazil. However, Bahrain's GP earlier in the season was the most watched last year, according to Initiative, with about 54 million live viewers.

While these TV audiences have been in reverse gear they are still strong compared with many other sports, although way short of the 350-360 million for Melbourne that AGPC chairman Walker trotted out for most of the past decade.

And much, much smaller than the numbers motor sport's world governing body, the Paris-based Federation Internationale de l'Automobile (FIA), used to put out in the 1990s.

At one time (and the announcements can still be found on its website) the FIA had an annual total global audience for F1 of more than 50 billion - several times the world's population, with an equally preposterous average of more than 3 billion a race.

Initiative's research is based on average audiences from the equivalent of Australia's ratings agency OzTAM in 55 countries. F1's TV footprint is wider than that, but Alavy points out that the 55 countries account for 95 per cent of world GDP - and, we suspect, perhaps an even greater percentage of TV sets.

For the Australian GP, Initiative reports 32.796 million live viewers last year - up 31 per cent, probably largely because of the later 5pm start to capture European viewers. But Alavy adds that the audience for delayed telecasts was down 36% to 12.983 million.

So Initiative's '09 total for Melbourne was 45.778 million (many TV industry experts would say even including the delayed watchers is charitable), up a mere 1 per cent from 45.391 million for '08, when the race began at 3.30pm.

Yet in 2007, the year of the last 2pm start in Melbourne (and the first year of retirement for Michael Schumacher, who is now back), the total from Initiative was 50.137 million.

What Initiative does is not rocket science. Rather it is a compilation of credible numbers from the key markets - something the Victorian government ought to have been demanding for years as a cross-check on the value of its GP - now costing its taxpayers $40 million a year.

Consider the numbers from Initiative against Walker's comments in his chairman's report in the AGPC annual report late last year.

Walker said the 5pm race start had been "of enormous benefit to Melbourne and Victoria".

"The new twilight race time generated the largest European broadcast audience ever for an Australian GP, with audiences nearly tripling in size," he said.

"In the United Kingdom the live coverage attracted 56 per cent of Britain's television audience, while France peaked at 46.5 per cent.

"Germany and Italy also obtained approximately 50 per cent of the television audience and Spain was a staggering 69 per cent.

"The new event timing worked well also for audiences in the big emerging markets of Russia, China, East Asia and the sub-continent, in particular India with a potential audience of some three billion not previously available to us."

Readers may note that Walker's numbers were not attributed to any source, although there were no obvious space constraints in the production of the AGPC annual report.

Initiative's Alavy says that, while there was "very considerable year-on-year growth in (live telecasts in) a number of European markets, in none of them was the growth rate as high as 300 per cent".

And the live increases were largely offset by falls in those watching delayed telecasts.

As stated at the outset, motor racing is a big sport.

Unfortunately many of its biggest promoters are even bigger, indeed much bigger, on bulldust.

And, until it starts dealing in something much closer to facts, it will struggle for credibility - with its own fans, and more importantly the broader public.