CD Bramall, number four dealer group in the AM100, has increased pre-tax profit by 9% to £11m for the six months to June 30.
Chairman Tony Bramall said: "With the economy still being driven by consumer demand and low interest rates we expect to see a strong third quarter of the year, which of course includes the new registration plate from 1 September.
"Unlike last year, when we saw prices of used cars falling dramatically, this year we should only see the usual seasonal decline which we have managed very well in the past."
Group turnover increased by 12.5% to £495.2m, compared to £440.2m last year. Operating profit is up 12.7% to £13.2m.
During the period, Bramall sold 18,088 new cars - an increase on the same period last year of 29%. Used car volumes increased by 12% to 13,700 units.
During the last half-year, the Bramall group added eight new dealerships to its chain, including two Ford and three Land Rover. Bramall was also awarded the Invesco truck franchise for Greater Manchester.
Mr Bramall will relinquish executive duties at the end of 2001, but remain as chairman.