Red plates are red-hot right now. Interest is revving up over cars with those distinctive red number plates marking them for off-peak use only, thanks to incentives starting on Monday.

These are longer usage hours - notably all day on Saturdays and the eve of five public holidays - plus cash rebates.

The changes are timely, coming in the run-up to Chinese New Year, when being able to drive around freely on the eve of a public holiday, instead of only after 3pm as currently permitted, is bound to accelerate interest.

Calls to the Land Transport Authority's (LTA) hotline about buying such cars have jumped from 30 a day to 150 since it announced in August last year that it would be perking up the 15-year-old Off-Peak Car (OPC) scheme.

Until then, car-crazy Singaporeans were happy to fork out bigger bucks for the greater freedom of unrestricted use of their dream machines.

Sure, owners of off-peak cars got a one-off $17,000 tax rebate, but they could drive only during off-peak hours, from 7pm to 7am on weekdays, among other aspects of the scheme.

Now that the scheme has been tuned up with features such as allowing unfettered use on the eve of New Year's Day, Chinese New Year, Hari Raya Puasa, Deepavali and Christmas Day, the brakes are off.

One car-owner whose interest is piqued by the off-peak changes is 28-year-old customer service executive Thomas Tay.

He feels that buying an off-peak car under the new scheme is worthwhile. 'That is because I don't really need to drive to work since my office is nearby, but I still want a car so that it is easier to go out after I knock off from work,' he says.

Bank manager Terrence Tham, 33, is considering getting an off-peak car after the scheme changes take effect on Monday. He says: 'My second child will be born next month and I need to ferry my parents around on weekends, so the sedan car I am driving now can't meet my needs.'

For some, there are obstacles to conversion. A driver who converts his normal car to an off-peak one will receive $1,100 in cash rebate for every six months it remains so, but not the $17,000 offset.

Mr Tham, who uses his car during office hours to meet clients, says converting it 'gives me only a regular rebate and not a lump sum, so there are immediate big financial benefits for me'.

Some car dealers expect a surge in interest from potential off-peak buyers.

A dealer from Hyundai agent Komoco Motors says: 'We expect sales of off-peak cars to account for about 15 per cent of our total monthly sales volume when the scheme starts, compared to current numbers of between 8 and 10 per cent.' He declined to be named.

However, Mr Chin Kee Min, 33, senior manager for Kia operations in Singapore, reckons that rising Certificate of Entitlement (COE) prices could be a red light to increased demand.

'People who are looking at off-peak cars are turned off by the high COE prices,' he says.

Although he does not expect COE prices to come down in the next three to four months, he is confident that 'customers will check out the cars once the market comes round to accepting the rates'.

Still, the number of off-peak cars on the road has been increasing. There were 47,224 off-peak cars at the end of last year, compared to just 5,308 in 2000, making up about 8 per cent of the total car population of about 560,000.

With the scheme changes, the LTA aims to raise this to 10 per cent.

Current off-peakers have a choice of staying in the old scheme or switching. The catch is that they must pay a one-time administrative fee of $100.

Monday's changes mean that these drivers, along with some new car buyers and owners of cars with no restrictions, are no doubt gearing up for some cost-benefit calculations.