Direct Line, the UK's biggest direct writer, posts a rise in pre-tax profits to £24m for the half year to 31 March compared with £9m for the same period the year before.
Gross premiums have risen to £581m, compared with £442m, while the average premium written was 12.5% higher.
Chief executive Ian Chippendale said the insurer now had the lowest cost base in the UK for personal lines.
He added: "Our internet business has grown dramatically since going live last September, and is currently attracting more than 150,000 quotes per month."
The motor book added another 400,000 customers, to bring the total to 2.8 million, and the number of home policies increased marginally from 930,000 to 945,000.
There was a healthy 20% rise in the number of travel insurance policies sold, to 69,000, helped by new legislation that untangled customers from tie-ins with tour operators.
Pet insurance policies have now reached 49,000.
Direct Line has an expense ratio of 18.5%, a loss ratio of 87.3% and an operating ratio of 105.8%.