Profit after tax was £1.3m a rise of 29% over the same period in 2003 (£1m).
Turnover increased by 32% to £348m (2003: £264m). Profit before tax was £2.2m (2003:£1.7m).
HR Owen operates 40 dealerships in 17 market areas. In the six months to June 30 it spent £1.2m on acquisitions, resulting in its highest ever level, the company said, of vehicle sales and aftersales activity.
But the company expressed a note of caution about the rest of the financial year.
In a statement HR Owen says: "Certain segments of the group’s markets look set to be more difficult in the second half of the year as rising interest rates have tempered both consumer and corporate demand.
"It has recently become apparent that new registrations during September will fall significantly below earlier expectations and the group will continue to be affected by the reorganisations of a number of the market areas which it operates.
"In some cases, these reorganisations are taking longer and proving to be more expensive and disruptive than anticipated.
"We now expect that, whilst the group will remain profitable over the year as a whole, the results for the full year will be substantially reduced by the trading performance in the second half.
"However, we remain confident that with the completion of the reorganisation of our market areas and a range of new models, our franchise portfolio is well positioned in the market to provide a sounds basis for profitable growth."