I just worked out by end of May/June that in the Sunderland fleet their will only be 13 buses which are not Gas and Enviro.

As Sunderland will have

41 Enviro buses
40 Gas
The other 13 - MAN and Darts?

Also in the press area of the stagecoach site:

GREEN GAS BUSES COME TO SUNDERLAND
Stagecoach North East in Sunderland is welcoming 17 new gas buses to the city in an official preview event on the 14th February 2014.

The 17 new gas buses will be officially on the road from late February following an investment from Stagecoach of over £2.5 million in buses and £1 million for the infrastructure at the Sunderland depot, which includes a gas plant for the fuel supply. The total investment of nearly £4 million was part-funded by a grant from the latest round of allocations from the Department for Transport’s (DfT) Green Bus Fund. - Seems their out in late February now... wrong?

The gas buses are a further extension of Stagecoach North East’s green agenda, as they will provide a cleaner, greener ride due to lower carbon emissions and therefore delivering a better living environment for the people of Sunderland. The 17 new gas buses follow the introduction of 21 new buses to the City in October last year.

The new biomethane gas buses in Wearside will be Scania/ADL Enviro 300 single-decker. All buses will be fitted with free Wifi.

Phil Medlicott, Managing Director, Stagecoach North East said: “We’re looking forward to the official launch of the gas buses and finally getting them on the road in Sunderland. The gas buses are a testament to Stagecoach’s green agenda as we continue to reduce our carbon footprint, and with the lower carbon emissions, it means a better environment for local people. We invite members of the public to come along to the Open Day, take a ride on the new buses and find out more about the unique way they operate through the process of anaerobic digestion.”

Members of the public are invited to the Open Day to view the new gas buses on the 14th February between 11am and 3pm. Rides will be taking place on the buses at 12pm and 1pm.

The 17 buses will be servicing routes 16 (Hastings Hill to Red House via city centre) and 20 (Pennywell to city centre).

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Past the date but thought i would share it