Worcestershire-based Halfords said it was encouraged by its prospects after reporting another strong sales performance.
The car and cycling parts retailer, which has more than 400 stores and 10,000 staff, said total sales grew by 9.3 per cent in the 26 weeks to September 29.
When stripping out changes to store space this showed growth of 6.5 per cent on a year earlier. The figures are broadly in line with trends seen in the summer, following growth in each of the company's sales categories.
It is likely that Halfords benefited from new rules making child car and booster seats compulsory for all children up to 12 years.
Although car seat sales make up only a small amount of Halfords' annual group sales, the firm is now a significant player in this £70 million market.
Analysts say Halfords probably has around a 20 per cent share of the market and a spokesman said it was now chasing Mothercare for the number one slot.
"Sales have already doubled," said chief executive Ian McLeod.
"We significantly increased our orders in time and we have substantial stocks."
Car seats accounted for around two per cent of sales last year.
Mr McLeod added that the company's overall sales and service strategy continued to deliver results.
He said: "We remain confident in the resilience of our business as demonstrated by these results, giving us encouragement for our prospects in the second half."
Halfords will provide further details on its performance at interim results on November 23.
Nick Bubb, a retail analyst at Evolution Securities, said he did not plan to upgrade his profits forecast of £81.5 million for the full year. The company reported profits of £77 million in its last financial year.
In light of the likely boost to sales from child seats, Mr Bubb said he had expected a stronger like-for-like sales figure. Same-store sales were ahead 6.6 per cent when Halfords updated the market on trading in the 17 weeks to the end of July.
But analysts at Merrill Lynch upgraded its full-year pretax profit forecast by £3 million to £83 million, while Investec analyst Mark Charnock raised his forecast by around £2 million to £77 million.
"Strong H1 sales, helped by new legal requirements for children's car seats, coupled with clear signs that gross margins are on the mend, means we will be upgrading," Mr Charnock said in a note.
Strong demand for bicycles and in-car technology has buoyed the company over the last year. It now provides one in three bikes sold in the UK and is also the market leader in the supply of car parts and satellite navigation systems.
Halfords' own brands include Ripspeed for car enhancement, and Bikehut for cycles and cycling accessories. Stores also offer fitting services for car parts, child seats and other products.