TV review: The Route Masters: Running London's Roads, BBC2

Luther, BBC1

"My best friend calls me the Bus Pimp," said Vicky, one of the more engaging characters in The Route Masters, "But I do get called Blakey too." This comparison had obviously occurred to the producers of this series about London's transport systems, too, because they'd called their final episode "On the Buses". I'm very glad to say that it was much funnier and sweeter than the original, in large part thanks to Vicky, who brings an earthy realism to her work as a route controller.

"We're not asking them to fart gold or anything," she said about the drivers she supervises from a central control room. "Just drive the bus on the time card if you can.... it's not a rocket-science job." No it isn't, Vicky.... it's bus science, but then that now involves a lot more than a clipboard and a suspicious nature. Every bus is monitored by video and GPS, its progress tracked from a control room that looks a lot more Cape Canaveral than you might expect.

The drivers don't much care for this, talking wistfully of the time when they were a law unto themselves once they'd left the depot. But when you heard some of the stories of the good old days, you couldn't help but feel that passengers should feel grateful for the new efficiency. One old driver recalled letting his conductor off to do a spot of grocery shopping halfway through the route. And Christine, training to drive a bus herself, remembered her father's happy memories of popping into the pub for a pint and some jellied eels, while his customers sat stalled at his convenience.

Others recited the numerous ways in which you could sabotage a double-decker if you didn't feel like working on a particular day. This episode ended with a crescendo of nostalgic sentiment for the old Routemaster bus, including the very touching affection of the engineer who keeps the surviving ones on the road. But even he couldn't persuade you that the system was better back then than it is now.

"I've seen something like this before," said Luther, in the opening minutes of the latest series of the show that bears his name. Boy, you can say that again. Here we go again with the solitary woman making her way home down darkened streets, doomed to end up as the plaything of a murderous psychopath. Here we go again with a killer who wallpapers his lair with evidence of his previous crimes.

And here we go again with the weary detective superintendant who appears to speak exclusively in procedural clichés. "It's out of my hands," he says, pulling Luther off the fetish killer case to chase down the murderer of an internet troll. "Don't make me regret it," he adds, when Luther improbably convinces him that he can work both enquiries simultaneously.

The twist for this series is that internal investigators suspect that Luther might be a kind of serial killer himself. His suspects appear to have an unfortunate habit of dying before they get to court, so his loyal sidekick Justin has been persuaded to keep an eye on his working methods, which include dangling reluctant talkers over the parapets of tower blocks. But I'm not convinced this twist is enough to make up for the gaping holes in the plausibility. At one point, the chief suspect for the troll murder chops his fingers off in a blender to avoid a fingerprint match that would incriminate him. You can believe that, in his panic, he might have forgotten that his flat will be absolutely coated in fingerprints. But not that the police will have forgotten it too. And though Luther delivers its gore and its dread with a certain amount of style, it too often falls back on the standard machinery. "What am I not seeing?" Luther asks himself as he stares at the investigation whiteboard in frustration. Anything fresh, I'd say.