More than 150 cars were stolen in Dyfed and Powys in the year to June, new figures show – as thefts rise across England and Wales.
A motoring group has called the rise in vehicle crimes "worrying for everyone".
However, this was a fall from the same period five years ago, when 165 such crimes were registered in the area.
The AA said the jump in car thefts is a cause for concern.
Gus Park, managing director for AA insurance services, said: "These figures are in danger of getting out of control, which if left to spiral further will have big cost implications in terms of the impact to wider society – let alone the price policy holders pay.
"We urge police chiefs and crime commissioners across the country to create an action plan to crack the case."
Mr Park further suggested drivers should avoid "giving miscreants an easy win", advising them to use steering wheel locks and parking in a garage when possible.
Across England and Wales there were 132,000 vehicle thefts in the year to June – up 13% from 116,000 the year before.
Dyfed-Powys Police is unique among police forces in having a relatively high charge rate for car theft – 17% thefts resulted in a charge in the area, while the national average is below 3%.
In the area, 35% of cases were closed without the force identifying a suspect, compared to 79% across England and Wales.
Superintendent Matthew Moscrop – part of the National Police Chiefs’ Council team on vehicle theft – said police chiefs are working to clamp down on the sale of technology used to break into vehicles, and to close routes for selling them once they are stolen.
He said: "Intelligence suggests a large proportion of vehicle theft can be attributed to organised crime groups and there have been a number of successful operations around the country which have led to the discovery of not only stolen vehicles but also ammunition and drugs."
"Tackling vehicle crime needs approaching from several different angles, and we can only achieve this through working closely with our partners in both Government and industry," he added.