He was hospitalised and discharged but subsequently lodged claims for weekly compensation payments, supported by regular medical certificates and supporting medical reports.
Mrs Brennan was subsequently granted attendant care payments as compensation for performing various duties for her husband.
Between December 1999 and August 2011 Mr Brennan was paid $665,696.89 in gross weekly compensation payments and between 2000 and 2003 his wife received $55,790 in weekly attendant care payments.
Mr Jenson said it was the Crown's case that over a period of 12 years the Brennans deliberately understated the level of Mr Brennan's ability to perform his usual functions, including his capacity to continue to take an active role in their business and carry on with his high-performance motor racing activities.
During that time Brennan competed in various motor racing meetings, including an international racing meeting in Thailand in 2010 in which he was the overall winner.
He continued to work on cars and gained a national qualification in automotive engineering, the crown said. The couple's alleged offending included Mrs Brennan also overstating the level of support she was providing to her husband, Mr Jenson said.
"The Crown's case is that Mr Brennan was able to function at a much higher level than what was being claimed in medical certificates, and that was self-evident to the Brennans when they presented documents to ACC and did so dishonestly," Mr Jenson said.
That was borne out by company records, and other documents, including numerous invoices charged for labour signed by him, he said.
Mr Jenson said the Brennans had claimed no one else in the country could perform the type of specialised work Mr Brennan had been doing and the business was struggling.
Yet forensic accounting evidence would show the business turnover before and after the injury had not altered significantly.
During the period of alleged offending Mr Brennan had also undergone various medical assessments including neuropsychological testing.
Mr Jenson said Mr Brennan had been "deliberately underperforming in testing" to enable him to maintain compensation payments. Medical evidence showed his "understated" test results were worse than someone suffering with advanced dementia and downs syndrome, he said.
In October 2011 ACC launched an investigation and ACC payments were subsequently suspended.
The trial continues today.