From 1974 the O305 received a more powerful engine and an epicyclic gear rear axle plainly audible by its distinctive singing noise.

In the mid-1970s, the Falkenried rolling stock manufacturer in Hamburg had developed a transmission concept with the engine and the power train placed in the rear part.

After Mercedes-Benz had acquired the patent, a 1977 prototype was deployed by the Hamburger Hochbahn public transport operator.

[2] For a long period of time, Hong Kong franchised bus operators were required by law to purchase double-decker buses produced in Commonwealth countries.

With newer buses (especially those with air conditioning) available for trunk services, the Mercedes were redistributed to North District and Tai Po and served there until their retirement on 22 November 2002.

A year later, SBS also took in a second Mercedes Benz O305 double-deck demonstrator with a prototype Alexander R-type body make that was previously exhibited at the 1982 Commercial Motor Show in the UK.

At 11.1 metres long and a licensed capacity of 109 passengers, they were the largest non-air conditioned double-decker buses in Singapore.

They entered service from 1984 to 1987 and were deployed to Ang Mo Kio, Toa Payoh and Hougang bus depots throughout their lifespan.

Transperth (as the MTT was rebranded in 1986) and its contractors began withdrawing this sizable fleet of O305s in October 1999 although it would be 2012 until the last were withdrawn.

Examples include 444, which featured a Mauri (Italy) body assembled locally by JW Bolton and 007, an experimental bus (model OG305) with an LPG-fuelled engine.

From the success of the trial gas buses, two O305s (270/1) were converted to LPG operation in the early 1980s, a CNG-fuelled O305G was ordered and entered service in 1987 as 009.

The first and second batches had bodywork completed by JW Bolton and Howard Porter and featured model OM 407h 240 hp (177 kW) naturally aspirated engines.

To overcome sluggishness, the buses in the third batch (also featuring Howard Porter bodies but built to the VöV-II design) were fitted with model OM 407hA 280 hp (206 kW) turbocharged engines.

The Public Transport Commission and its successors operated the largest fleet of O305s, purchasing 1,287 O305s and 30 articulated O305Gs, all bodied by Pressed Metal Corporation for use in Sydney and Newcastle.

[10][12] The revisions to the body were minor, and the most noticeable were a return to four-piece sliding windows to improve ventilation and to 203mm high route numbers at both the front and rear after the 127mm examples proved unpopular.

All were sold to private bus companies mainly in the Sydney and Melbourne metropolitan areas with 12 being exported to New Zealand to operate in Auckland and Wellington.

[26] Luton Airport purchased three O305G articulated buses in 1988 with Lex Services bodies based on Heuliez framing delivered in April 1988, they were fitted with only 35 seats allowing for large amounts of standing and luggage space.