You've ignored inflation.- Just worked out if a private sector worker starting on €20,000 a year, invested 6.5% of their salary for 40 years, they would have €322,621 at the end. This assumes growth of 6% per annum and a pay increase of 3% each year.
If you want a salary growth of 3% - it's likely inflation around 3% as well. In that case the present value of 322k using the rest of your figures would be 100k.
However Irish life use a figure of 3.35% - 0.7% for charges as their current assumption for fund growth. For salary growth the use 1.5% and inflation @ 2.5%
With Irish life pension growth figures I'd guess the PV of someone on 20k putting 6.5% per annum away at more like 70k as an end fund.