An increase in personal injury claim payouts, vehicle repair costs and thefts resulted in the third quarter of this year being the third most expensive on record for UK motor insurers.
That is according to data from the Association of British Insurers (ABI), which reveals they paid £2.1bn to customers between July and September - the third highest quarterly amount on record.
This comes after the government decided earlier this year to cut the discount rate from 2.5% to -0.75%, with the costs of personal injury claims subsequently rising 6% between the second and third quarter of 2017 to £835m.
"Increasing cost pressures continue to put the squeeze on motor insurance premiums, pushing up the average cost of cover to record levels and hitting young drivers particularly hard," ABI assistant director, Rob Cummings, said.
The data shows that vehicle repairs, including third party claims and windscreen damage, cost insurers just over £1bn between July and September, making it the highest quarterly figure recorded.
This is 16% higher than during the same period in 2016, with the average cost of repairing damaged vehicles found to have jumped by 46% to £1,944 since the second quarter of 2013.
The ABI said this was being driven by higher costs for imported parts due to the fall in the value of the pound, and the increasing complexity and technology of many vehicles.
In addition, theft claim costs totalled £71m in the third quarter of 2017, up 25% on the same period last year, with the average claim reaching an all-time high of £6,582.
This was reflected in figures from the Office for National Statistics showing that vehicle-related crime rose 17% in the year ending June 2017, which is thought to coincide with high-tech devices enabling cars to be stolen without force.
With mounting costs putting more and more pressure on motor insurance premiums, Cummings said government proposals to reform the discount rate "cannot come soon enough".
"It is vital that the government pushes ahead without delay on its proposals, as well as implementing changes to the rules governing payouts for less serious soft tissue injuries like whiplash," he added.