Traditional engine cars have been converted to electric vehicles by Mexican company High Performance Automotive (HPA), claiming the process is much cheaper than purchasing an entirely new vehicle.

HPA installs lithium or lead acid batteries in internal combustion vehicles that are connected in series to form banks with voltages ranging from 48 to 144 volts which determines the top speed of the car.

The technology has been tested in 10 vehicles so far and top speeds exceeding 100kms per hour have been achieved, which is suitable for urban areas.

The electric vehicles were found to be significantly cheaper than their traditional counterparts.

The team found that drivers would typically spend 500 pesos a week on fuel (£20) for an automobile with an internal combustion engine compared to the converted vehicles that cost about the same amount every two months.

The cost of converting vehicles is currently high at 130,000 pesos (£5,300), especially for a relatively poor country like Mexico, although this would be brought down if the process was commercialised.

"We [install] the engine, controller, batteries, transmission adapter plate, power cables and charger so that people can have a ready to run vehicle", said Ruiz Garcia, a graduate from Mexican university UNAM, who worked on the project.

The conversion process begins with the extraction of the internal combustion engine, after which an electric motor is adapted to fit the vehicle and space is allocated to house the battery bank.

"Currently the cost of new electric vehicles are not accessible, over half a million pesos, this aroused my desire that society has access to this technology," said Hector Ruiz García, director of HPA.

After conversion, the vehicle can be connected to any existing socket and has an expected lifetime of more than 10 years.

"There is no limitation on the size of the car, only larger, more investment is required, but can make any conversion,” Garcia added.

"The importance of these conversions to electric cars resides in demonstrating that this is a technology available to everyone. Our intention is that the vehicle fleet is not increased, but rather existing and obsolete and are reused to generate both economic, social and environmental benefits.”

Global electric vehicle sales are increasing at a slower rate than previously predicted, although improving technology and reducing costs are helping to increase take-up.

Germany introduced a discount scheme to encourage electric vehicle buyers earlier this year that saw almost 2,000 people take advantage in the first month alone.