London's first electric taxi has hit a bump in the road

But the plug hasn't been pulled

The first electric taxis due to operate in the capital have been delayed, after a fault was found in the all-important meter that tracks time and distance driven.

London has only permitted zero-emission vehicles to join its official fleet of 23,000 cabs from the start of this year, but so far only one has been licensed - and it hasn't yet successfully carried a paying passenger.

The only approved model so far is the TX eCity from LEVC (formerly The London Taxi Company), but despite several hundred being ordered from the Chinese-owned firm, it will be several weeks before they are delivered.

The problem is due to a fault in the meter that determines payment at the end of the journey. The electric car sends a regular pulse to the meter to track distance travelled, but it appears that the readings from vehicle and meter are not tallying. A spokesperson told The Guardian, "The signal from the vehicles and the meters are not lining up and we are working on a solution to fix that issue. We're working to get an appropriate converter to get the vehicles licensed by [Transport for London] and over to customers."

Although the TX eCity does contain a 1.3 litre petrol engine, this is only used as a generator for the battery pack and electric motor. The car can travel up to 70 miles on a single charge, but a full tank of petrol extends that to almost 400 miles.

WiFi and USB charging, as well as support for contactless payments (the latter being a popular argument against using traditional black cabs), are included, and a sat nav is also built in. This can inform drivers about congestion and nearby charging points, which cabbies have complained about in the past.

Steve McNamara, general secretary of the Licensed Taxi Drivers' Association, told The Guardian, "The lack of charging infrastructure is a concern. There are still nowhere near the number of rapid charge points that we need in central London."

There are only 90 rapid charging points in London today, mostly outside the central city. TfL has promised that 300 rapid points will be in use by the end of 2020, many reserved for taxis.

Although McNamara praised the design of the electric car, he also highlighted the additional £12,000 that it costs compared to a traditional taxi.