Mattias Ekstrom says new DTM tyre rules is biggest challenge for drivers

Under all-new technical regulations for this year, all DTM cars will use larger wheels and wider tyres than the previous generation of machinery.

This, coupled with reduced aerodynamics, means that the balance of grip generated by each car will be more mechanical than aerodynamic. And Audi ace Ekstrom says the change of driving style this requires in the new A5 DTM has taken time to adapt to.

"The car is definitely a bit different to drive than the A4," said the two-time DTM champion. "The biggest difference is made by the new Hankook tyre which is a bit wider - that changes the driving style to some extent.

"We've also got the gearshift on the steering wheel now [as opposed to a stick]. That also makes a bit of a difference, although there are many things you can't judge at the moment because we haven't driven the final version yet."

Ekstrom, who has been heavily involved in the A5's test programme, said that the car was at the point in its development where only small tweaks will be needed to it ahead of the March 1 homologation deadline.

"But principally speaking there's only fine-tuning work left at this stage. The key decisions were made a long time ago," he added.

"Every manufacturer will now try and guard their little secrets up to the last moment. After March 1 the cards will be revealed a little more - also during the track tests."