London's so-called "New Routemaster" - otherwise known as Boris Buses - could have some big and potentially dangerous faults, according to dossier produced by bus drivers themselves working at the Holloway Bus Garage.
Writing on MayorWatch transport expert Christian Wolmar, who is currently running for the Labour London Mayoral nomination, revealed details of what he claims are "major faults" that could "put passengers lives at risk".
Apparently the problem is with the batteries on the hybrid buses not working as they should. Battery failure means that the buses are actually essentially working the same as normal diesel buses "90% of the time". This is bad not just for the environment and for pollution, but it could also cause potentially dangerous problems when driving the buses.
For example, apparently without battery power the buses are slower to pull away from bus stops, and scarily the buses are prone to engine spluttering when the accelerator is hit - meaning that if buses are on an incline they could conceivably roll backwards when the driver takes the hand-break off.
The problems also cause congestion and delays (as buses move off slower) - apparently in some cases buses will disengage from the gears, requiring the whole bus to be restarted, which takes up valuable time.
If all of the batteries were to be replaced, it could cost as much as £20m.
As you might imagine, Transport for London (TfL) isn't too happy about these claims, and has already responded. Managing Director of Surface Transport Leon Daniels told MayorWatch that Metroline, which operates many of the new buses "are not aware of any issues arising from changes between electric and hybrid modes in service and they have had no such problems reported to them by their drivers", and claims that a new battery design has been introduced on new buses - with old batteries replaced as part of existing warranties at no cost to the taxpayer.
As Wolmar notes, this is latest in a long line of problems with the vanity buses - in addition to costing a lot of money, they are also criticised every summer for being far too warm. Unlike the old buses, windows on the bus do not open.
Full Disclosure: I donated somewhere between £10 and £20 to Christian Wolmar's London Mayoral campaign about six months ago.