Lookers took in around £350 million from its 11 outlets in Scotland trading under the Taggarts and Lomond brands, out of a turnover for the business as a whole of £2.5bn for 2013, a 19% increase on last year.
This helped the group to a 27% rise in pre-tax profit to £43.9m and financed a 10% rise in its total dividend for the year to 2.58p.
Mr Bruce said of trading in Scotland: "It has been fantastic. It is not down to the economy being particularly good or bad in relation to the rest of the country.
"It is driven largely by the brands we represent."
Lookers' Audi outlets in Edinburgh, Glasgow, Stirling and Perth are doing "extremely well", Mr Bruce said 18 months after Lookers bought them.
Such is demand that he expects to sell as many as 6000 Audi vehicles this year.
"Scotland has become a meaningful part of our overall business," he said.
Lookers acquired a Volkswagen van centre in Baillieston at the end of last year on the collapse of rival Verve into administration. It plans to expand this into the south side of Glasgow.
It is also intending to open an Audi dealership in Hamilton.
Mr Bruce said that 77% of its new car sales are backed by finance deals in which customers effectively lease their vehicles as car manufacturers offer packages in the hope of repeat business when deals come to an end.
He added that there had been a cultural change, citing the willingness of more people to take out mobile phones on contract rather than buy handsets.
"We are a more disposable society. The need to own assets is less meaningful," he said.
He said he expected conditions to remain favourable as new car sales are still behind where they were before the financial crisis.
Lookers' shares closed up 6.25p, or 5% to 136p.