The company says that around one in 25 of its standard 7.5 tonners is now equipped with a digital tacho but that the average utilisation rate for them is significantly lower compared to mechanical tacho versions.

Sean Welham, marketing director at TLS, said: "Renters just don't want digital tacho vehicles at present, despite the fact that it is now more than four months since they were made mandatory on new vehicles.

"When we speak to a customer to agree a rental, the vast majority do not have a driver card and so require a vehicle that has an old style tachograph. The growing need to have a card is just not on the radar of many operators and their drivers."

Figures obtained from VOSA by TLS show that less than one in 10 of UK drivers qualified to drive HCVs have been issued with a driver card.

Welham continued: "Even if a fraction of the drivers who are able to drive HCVs are currently active, then the take up of driver cards still appears to have been pretty low. There is a lot of ignorance around on the subject but also many drivers appear to be trying to do without hassle and cost of applying for a card for as long as possible.

"We are trying to help by keeping driver card forms at all our branches and will even take customers through the process of completing the application. This is something that we are actively encouraging in order to get more of the newer vehicles on rent."

The problem is likely to become more acute over the coming months as commercial vehicle rental companies like TLS take on more and more digital tacho vehicles.

Welham said: "While the vast majority of our truck fleet is now mechanical tacho equipped, the average age of 7.5 tonner on our fleet is 18 months, so it will not be too long before we have significant numbers of digital tacho vehicles to rent.

"It will only be a matter of month or a year before drivers who want to rent a 7.5 tonner will need to have a driver card or they will simply find it difficult to get hold of a vehicle. The take-up must increase quickly."

Welham added that TLS was working hard to make customers aware that their drivers needed to obtain driver cards very soon or that problems were likely to ensue.

He added: "Our feedback about cards is that drivers will only get one when they believe they really need one - but that time could be much sooner than they believe."