Nearly three out of 10 non-negotiators (29%) said this was because they either do not know how to, are concerned about insulting the seller or do not feel comfortable doing it, the research indicated.
Drivers aged 18-24 are the least likely to haggle with just 1% negotiating a discount themselves, the poll suggested.
Chris Knapman of CarGurus said: "While some people enjoy the art of the deal, there are clearly thousands of buyers out there who may not be comfortable knowing how to negotiate, or simply don't want to.
"Not so long ago, a person's ability to negotiate could have been all that stood between them getting a great deal on a used car or paying over the odds.
"Luckily, the modern car buying process means you no longer need to be a master negotiator to secure a great deal."