The 1905 International Tourist Trophy was an automobile motor race held on 14 September 1905 on closed public roads along the Highroads Course on the Isle of Man.

The Automobile Club wanted to run an event to help develop fuel efficiency in motor cars and opted to use the same route as had been used for the trials.

Less than half of the cars completed the full 208.5 miles (335.5 km) and there were more retirements due to mechanical failures and crashes than a lack of fuel.

The Highway (Light Locomotives) Bill was rushed through the Tynwald in March 1904 but only allowed racing for three days during that year, specifically for the Gordon Bennett trials to take place.

The bill gave provision for six days of racing to take place; three for the Gordon Bennett trials in the spring, and three for the Tourist Trophy in the autumn.

[3] The course used for the race was the same as had been used for the 1904 and 1905 Gordon Bennett trials, a 52.125-mile (83.887 km) course featuring over 420 corners which followed much of the modern day Snaefell Mountain Course, known as the Highroads Course (or Highlands).

The lap began at Quarterbridge in Douglas and proceeded down the A5 road towards Castletown, then back up the A3 to Ballaugh where it then headed towards Jurby along the A10, but turned onto the A13 towards Ramsey.

[8] Most of the cars opted to use Continental tyres; just the Maudslays and Napiers used Palmer, the Whites and Swifts used Dunlop, while the Wolseley and Darracq vehicles used Michelin.

Of the 58 original entrants to the event, ten pulled out before the entry list was published,[10] generally because they either could not reduce the weight of their car sufficiently to be within the limits, or they could not achieve the required fuel efficiency.

[18] There were also a number of accidents during the practices; Ernest de Wilton crashed his Swift into a stone wall near Castletown, causing significant damage to the car.

[16] Another of the competitors, A. McCormack in a Gladiator, hit some cows after coming off the road, and caused such damage to the car's brakes that it could not be repaired in time for the race.

[15] On the Sunday prior to the race local residents were upset that forty of the cars were driving the course, and meetings were held where they expressed their indignation that it was a "desecration of the sanctity of the Sabbath".

[18][20] Due to the fuel-saving nature of the event most of the drivers began the race by letting their car coast down the initial slope under its own momentum before engaging gear.

[18] There was further speculation of foul play when it was discovered that Arnott's Minerva had been tampered with; two spark plugs had been smashed and an air valve bent, causing his engine to overheat.

[21] At Keppel Gate on the Mountain Road, Frederick Bennett, who had been unable to take part in the practice sessions and therefore did not know the course very well,[15] approached a corner with too much speed in his Cadillac and crashed, ripping off two of the wheels.

Along with the withdrawal of France and Britain from the Gordon Bennett races, and the amount of support for the Tourist Trophy, they commended the Automobile Club for "[recognising] the changed conditions of affairs.

Though he conceded that the concept of the race had been admirable he felt that the cost of fuel was negligible in the running of a motor car and that other factors, such as general reliability over a thousand or more miles, were more important.