Car buyers are slashing an average £939 off asking prices price, a survey by Auto Trader magazine has found.
It found about 60% of motorists paid under the asking price for a new or used car in the period July to September 2012.
The survey found male buyers managed to get an average of £1,029 knocked off the price of a new or used car, with women managing £706.
However, the poll of more than 3,000 motorists also showed 51% of sellers chose the most convenient way to sell rather than a method that could have got them the best price.
Auto Trader group director Nathan Coe says: "With so many sellers getting less than they were expecting for their cars, it raises the question of whether this is people not valuing their cars appropriately or whether it's buyers taking advantage of a weak market.
"Everyone knows buyers look at the state of the market before they purchase, but consumers have a lack of understanding about accurate pricing when it comes to selling. Sellers should do research through online valuation sites to prevent disappointment."
However, Auto Trader warns the market is beginning to pick up for sellers, so buyers should not become complacent.