France had the largest automobile industry in Europe at the time, and in an attempt to better reflect this the Grand Prix had no limit to the number of entries by any particular country.

Hot conditions melted the road tar, which the cars kicked up into the faces of the drivers, blinding them and making the racing treacherous.

[3] Entries were limited to three per country, which meant that although the nascent motor industry in Europe was dominated by French manufacturers, they were denied the opportunity to fully demonstrate their superiority.

[4] The French governing body, the Automobile Club de France (ACF), held trials between its manufacturers before each race; in 1904 twenty-nine entries competed for the three positions on offer.

Under the ACF's proposal, France was allowed fifteen entries, Germany and Britain six, and the remaining countries—Italy, Switzerland, Belgium, Austria and the United States—three cars each.

Competitors then took the Fourche hairpin, which turned sharply left and slowed the cars to around 50 kilometres per hour (31 mph), and then an essentially straight road through Bouloire south-east towards Saint-Calais.

A series of left-hand turns took competitors back south-west towards Montfort on the last leg of the triangle, a straight broken by a more technical winding section, near the town of Connerré.

[11] The road surface was little more than compacted dust and sharp stones which could be easily kicked up by the cars, and to limit the resulting problem of impaired visibility and punctures the ACF sealed the entire length of the track with tar.

Ten French manufacturers entered cars in the Grand Prix: Clément-Bayard, Hotchkiss, Gobron-Brillié, Darracq, Vulpes, Brasier (the successor to Richard-Brasier), Panhard, Grégoire, Lorraine-Dietrich and Renault.

[20] In the Grand Prix's one major technical innovation, Michelin introduced the jante amovible: a detachable rim with a tyre already affixed, which could be quickly swapped onto the car in the event of a puncture.

[12] Renault's lead driver, the Hungarian Ferenc Szisz, started next, and behind him Victor Hémery of Darracq, Paul Baras of Brasier, Camille Jenatzy of Mercedes, Louis Rigolly of Gobron-Brillié and Alessandro Cagno of Itala.

Philippe Tavenaux of Grégoire, scheduled next, was unable to start; the only other non-starter was the sole Vulpes of Marius Barriaux, which was withdrawn before the race when it was found to be over the weight limit.

As the day grew hotter the tar began to melt, which proved to be a greater problem than the dust; it was kicked up by the cars into the faces of the drivers and their mechanics, seeping past their goggles and inflaming their eyes.

[5][25] The Renault driver, J. Edmond, was particularly affected: his broken goggles allowed more tar to seep past and rendered him nearly blind.

Seventeen cars completed the first day; Henri Rougier's Lorraine-Dietrich finished last with a time of 8:15:55.0, 2+1⁄2 hours behind Szisz.

[27][28] All the cars that were competing the next day were moved into parc fermé, a floodlit area guarded overnight by members of the ACF, to prevent teams and drivers from working on them until the following morning.

[27] Jenatzy and Lancia, who were both experiencing eye problems from the first day, had intended to retire from the race and be relieved by their reserve drivers.

[30][31] Panhard driver Georges Teste crashed early in the day and retired, as did Claude Richez of Renault; the sole Gobron-Brillié of Rigolly suffered radiator damage on lap seven and was forced out of the race.

[32] Szisz's Renault suffered a broken rear suspension on the tenth lap, but his lead was so great (more than 30 minutes) that he could afford to drive cautiously with the damage.

He took the black flag of the winner at the finish line after a combined total from the two days of 12:12:07.0; he had also been quicker on the straight than any other driver, reaching a top speed of 154 kilometres per hour (96 mph).

[34] Of the other retirements, Hémery, René Hanriot (riding mechanic Jean Chassagne) and Louis Wagner of Darracq suffered engine problems; the radiators on the cars of Rigolly of Gobron-Brillié, Xavier Civelli de Bosch of Grégoire and Cagno of Itala failed; Pierre de Caters of Itala, Shepard and Hubert Le Blon of Hotchkiss, A. Villemain of Clément-Bayard and Vincenzo Florio of Mercedes withdrew after wheel failures; Gabriel of Lorraine-Dietrich, "de la Touloubre" of Clément-Bayard and Henri Tart of Panhard retired because of other mechanical problems; and Fabry of Itala, Weilschott of FIAT, Teste of Panhard, Richez of Renault and Jacques Salleron of Hotchkiss suffered crash damage.

In an interview after the race, Szisz reflected on the "anxiety" he had felt as he drove the final laps: "I feared something small which would take away victory at the moment when it had seemed to be won.

[note 5][34][38] The ACF decided that too much pressure had been put on drivers and riding mechanics by forbidding others to work on the cars during the race.

Clément had driven the only Clément-Bayard to not have the rims, and it was thought that this contributed to Nazzaro passing him on the second day as he stopped to change tyres.

[40] The publicity generated by the race prompted the German governing body to organise a similar event that favoured their own industry.