Q: I use a walker and when I enter a New York City MTA bus through the rear door wheelchair lift, the bus driver asks me to come to the front of the bus with my walker to swipe my MetroCard, which I find both difficult and dangerous. Is there an MTA rule requiring me to do this? I would gladly allow the bus driver to swipe and return my Metro-Card, but I understand there may be an MTA rule against this. Is this true?

A: New York City Transit bus drivers have been instructed in a bulletin sent to them earlier this year to swipe the MetroCards of disabled passengers when requested to do so. That is the key: A driver will not offer to swipe your card, so you must ask. Once asked, he cannot refuse. A spokesman for New York City Transit, James Anyansi, said that riders should report bus drivers who do not comply with this request by taking down the bus number (located above the stop requested sign and on the outside of the bus) as well as the date, time, and route the bus was on. “We definitely want to hear about it because that is their job,” Mr. Anyansi said. “We would take appropriate disciplinary action.” Fortunately, the “low floor” buses, including all hybrids, have the wheelchair lift at the front of the bus, making it easier for people to swipe their MetroCards themselves.

Q: Yesterday I took a hybrid bus on the no. 4 route from the Cloisters. Much of the route was downhill, but the diesel motor was audibly running the whole time. When does electric power kick in? Does it ever drive the bus without the diesel?

A: The diesel engine you heard does not drive the motor of the bus. The hybrid buses are driven by an electric motor, the director of research and development for the department of buses, Gary LaBouff wrote in an e-mail. The diesel engine is part of a generator that powers the batteries that in turn power the motor. The diesel generator is always on because it also powers the air conditioning, air compressor, power-steering hydraulic pump, and provides heat, Mr. LaBouff wrote. When the batteries need charging, the engine runs faster to provide more generator power to keep the batteries charged. This is different than a hybrid car, which can putter along in virtual silence because the gas engine only kicks in at faster speeds or when the battery power needs a little juice. Mr. LaBouff wrote that hybrid-electric buses currently in use are consuming 30% less fuel on average than conventional diesel buses.