Efficient was foaled in 2003 by Sir Patrick Hogan's outstanding sire Zabeel from the mare Refused The Dance (by Defensive Play USA). He is a half brother to Guillotine, winner of the 2008 MVRC Dato Tan Chin Nam Stakes. By winning the 2007 Melbourne Cup he joined his father's other two past winners, in Might And Power (1997) and Jezabeel (1998).

In his first campaign as a three-year-old in the spring of 2006, Efficent put together five consecutive wins including the Gr.2 AAMI Vase at Moonee Valley and ending with a win in the VRC Derby by 2½ lengths ridden by Michael Rodd, beating home Gorky Park. After a rails runs well back on the inside, Rodd swiftly maneuvered the grey and Efficient bolted past the challengers with ease. Following his Derby win Efficient was entered into the Melbourne Cup field, run three days later. However, he did not pull up well enough, so was scratched from the race and spelled instead. Returning in the autumn Efficient had a very lightweight campaign of just two starts. In the 1400 metre Gr. 3 Schweppes Cup he finished fourth behind Haradasun and fifth behind Miss Finland in the Gr.1 Australian Guineas over 1600 metres.

As a four-year-old in the Spring of 2007, Efficient resumed in the Memsie Stakes at Caulfield and ran 10th beaten 7 lengths. At his next start he ran fourth in the Gr.2 Dato Tan Chin Nam Stakes behind El Segundo and Haradasun. He then ran unplaced in the 2000 metre Gr.1 Turnbull Stakes. Three weeks later Efficient lined up in the Weight for Age Gr.1 Cox Plate over 2040 metres at Moonee Valley where he finished 9th beaten 6½ lengths by the winner, El Segundo. Efficient's next start was the Melbourne Cup, his first start in a handicap race since his first campaign. He dropped 3 kg from the Cox Plate run to carry 54.5 kg. Due to his poor recent form he was sent out a 16-1 chance.

Reunited with jockey Michael Rodd for the first time since their 2006 Victoria Derby win, Efficient settled back in the field and travelled well. In the final stages of the race, he made a significant late surge to run down the British contender, Purple Moon, by a narrow margin of half a length. The Irish-trained lightweight horse, Mahler, secured the third position after maintaining the pace throughout. His win dividend of $22.70 was the biggest for a Melbourne Cup winner in thirteen years since Jeune in the 1994 Cup. Efficient became the first grey to win the Melbourne Cup since Subzero in 1992 and the first horse since Phar Lap to win the Cup after winning the Derby the previous year. Phar Lap won the 1930 Melbourne Cup the year after winning the 1929 Victoria Derby. Efficient was trained by expatriate New Zealand trainer Graeme Rogerson to win the cup, but switched to John Sadler soon after Rogerson decided to part company with the horse's owners, a syndicate headed by Lloyd Williams.

Efficient had an injury-plagued career after his Cup win, and was withdrawn from both the 2008 and 2009 Melbourne Cups in the fortnight leading up to the race. However, he did gain a third Group One success in the 2009 Turnbull Stakes, giving young jockey Nick Hall his first G1 victory. After this success, Efficient did not race for almost two years. He returned to racing in September 2011 but did not show any form until he ran second to Niwot in the 3200 metre Sydney Cup at Randwick in April 2012. On 4 October 2012, Efficient's owner Lloyd Williams announced that the horse had suffered a recurrence of an old injury and had been retired. Currently, he resides with other former champion horses at Living Legends, the International Home of Rest for Champion Horses situated in Woodlands Historic Park, Victoria, Australia. He occasionally makes public appearances at events such as the Melbourne Cup Parade.

RACE RECORD - 29:7-1-0

EARNINGS - A$4,788,525

Victoria Derby (2006)

Melbourne Cup (2007)

Turnbull Stakes (2009)

Australian Champion Stayer (2007/08)