The change of registration plate last month has led to a significant influx of part-exchanged cars and put residual values under pressure.
Adrian Rushmore, managing editor at EurotaxGlass’s, predicts used car prices will fall, on average, by at least 3% during May.
This follows a steady erosion of prices since October of last year at a slightly more accelerated rate than for the same period 12 months earlier.
“The deterioration in market conditions has conspired to increase depreciation,” said Mr Rushmore.
“The average three-year-old car will lose around £700 more from its original new price in 2008 compared to 2007, and this is reflected in the lower prices that dealers are asking for cars.”
The increase in supply of used cars also has implications for those defleeting.
“In most instances, current dealer stocks are more than adequate to meet demand, so the best prices will only be paid for those vehicles that offer a desirable combination of popular colour and specification, and are also in excellent condition,” said Mr Rushmore.
“If, for example, there is a need to rectify any damage to bring the car to a marketable condition, they are likely to mark down its value more heavily at present.”