Car prices achieved at auction in the first quarter reached the highest level since 2005.
According to a BCA assessment of January-to-March, a strong performance in the first two months saw an index figure five points up year-on-year.
However, the Pulse report said: "These rises mask a certain fragility in market conditions and have been achieved against a backdrop of continuing economic pressures and reduced sold volumes.
"It may be some time before the market repeats the steady value evolution seen between 2005 and 2007."
The price index is based on a Q1 2005 average value of £4,780.
Additional headline figures in the Pulse report:
* The average value of a used car in Q1 2012 was £6,114 - the highest ever recorded in the first quarter Q1 2005
* Fleet and lease values increased steadily during Q1 2012, reflecting the structural shortage of supply affecting the market
* The part-exchange sector established record monthly and quarterly average values in Q1
* The average ages of used cars when sold peaked at more than 61 months in Q1 2012, after three consecutive quarterly falls
* The age and mileage of fleet and lease stock sold at BCA climbed in Q1.