Off Peak Cars population in Singapore is increasing. Many have been attracted by the one-off S$17,000 rebate on their car purchase prices. Road Tax is only S$50 per year compared with normal car whose road tax are more than S$800.

Off Peak Car has restriction on its usage time. You can drive the Off Peak Car freely on Sundays, Public Holidays and during the following non – restricted hours:

Weekdays from  7:00pm to 7.00am
Saturday and Eve of 5 Public Holidays* starting from 3.00pm on wards

*New Year, Lunar New Year, Hari Raya Puasa, Deepavali and Christmas.

You can drive from 3PM on other eve of Holidays also but you need to call up LTA at 1800-CALL LTA(1800-2255582) to confirm. In addition, you can also check whether you can drive on Monday if the Holiday falls on a Sunday.
For example, this year National Day 2009 is on Sunday. The following day which is a Monday is also free for usage without the need for a supplementary licence. 

Supplementary Licence
This licence which cost S$20 allowed you to use your car during restricted hours. So you can actually still use your car within the restricted hours just like normal car. This supplementary licence can be bought at all SingPost Post Office.