Each bus has a toilet, allowing fewer stops which will cut journey times between Auckland and Wellington to just under 10 hours - at least an hour less than other bus operators - and free Wi-Fi and power connections to every seat.
ManaBus is not alone in offering $1 deals, Naked Bus and InterCity also offer the cut price fares.
But Sir Brian, who pioneered 1 fares with his MegaBus venture in Britain, says his larger buses will allow him to supply more low-cost seats than his competitors.
"There will be a larger number at lower price ranges - people may get seats for $5, $8 or $12," he said.
Brian Souter. Photo / Brett Phibbs
He was coy about indicating his upper price range, saying that would depend entirely on demand.
Naked Bus says its fares between Auckland and Wellington for a new sleeper service it will introduce in December, for which each of 40 seats in designated overnight buses will be convertible into a bed, will range from $1 to $55.
Although the lowest Naked Bus fare the Herald could find for the route yesterday on the company's website was $17.99c for late January, founder Hamish Nuttall said a new batch of $1 fares for February to March would be posted next week.
The next $1 fare the Herald could find for InterCity was for a return night trip from Wellington on February 10.
But executive John Thorburn said lower fares were just one of a number of considerations, others being the breadth of a bus operator's network and its level of service.
Another was baggage, for which his company offered a "very generous" free allowance of two 25kg checked bags as well as a 5kg carry-on item.
ManaBus offers just one 15kg checked bag and a carry-on item.
A Naked Bus offer of one free checked bag up to 20kg will end on November 24, when a $5 fee will be introduced, which Mr Nuttall says will allow him to reduce fares.
Sir Brian operates almost 12,000 buses and trains through various business interests across Britain, Europe and the United States.
He owned Auckland's main bus fleet for about 16 years until 2005 under his Stagecoach brand, then returned a few years later to buy the Howick and Eastern operation and Fullers ferries.
Mr Nuttall said Naked Bus intended introducing toilets to its fleets, and would reduce travelling time on some services in December.
He and Mr Thorburn of InterCity welcomed the new competition as giving a higher profile to bus travel in a very car-oriented society.