But the survey revealed there is still a high level of confusion about the features offered, particularly the government's contribution in which people can get up to $521 per year.
Of 16 true or false questions asked as part of the study respondents on average got just half correct.
One in 10 people were unable to answer any statements correctly.
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In its full analysis of the research Mercer said this was "concerning" and suggested working New Zealanders needed further help in understanding features associated with KiwiSaver.
The questionnaire revealed high levels of knowledge about the $1000 kickstart which the government gives to all those who sign up to KiwiSaver and the fact that people can contribute at 3 per cent, 4 per cent or 8 per cent.
Awareness was also high on taking money out of KiwiSaver to buy a first home and the ability to stop contributing if a saver experienced significant financial hardship or serious illness.
But 64 per cent of those questioned did not know the answer to a question about whether the government subsidised fees and 62 per cent did not know the answer to a question about the government's contribution - called the member tax credit.
The Government announced it would no longer pay a $40 fee subsidy in 2008.
While savers over the age of 18 can receive a lump sum payment of up to $521 if they contribute $1043 in the year to June 30 from the government called a member tax credit.
Mercer said the results suggested some New Zealanders were missing out on money they were entitled to.
The sentiment index revealed 38 per cent felt either positive and embracing about KiwiSaver or positive but reserved, slightly down on 39 per cent in 2012.
But those who felt sceptical about the scheme had increased from 31 per cent to 38 per cent. A further 24 per cent were actively against it down from 30 per cent in 2012.
Mercer said those who viewed the scheme negatively based that view on a lack of faith or trust in the government to ensure funds would be available during their retirement.
KiwiSaver is not government guaranteed.
Of those questioned 71 per cent rated KiwiSaver as a good, very good or excellent way to save for retirement.
Of those who rated KiwiSaver as a fair (13 per cent) or poor (5 per cent) way to save for retirement concerns centred around the perceived lack of guarantee and future viability of the scheme.