Holden star unsure of pre-Bathurst upgrade

Holden drivers are confident aerodynamic changes to their Commodores have closed the gap on Ford's runaway Mustangs ahead of this weekend's Supercars showpiece, the Bathurst 1000.

But Holden star Shane van Gisbergen is not so sure.

Van Gisbergen looked to have been one of the great beneficiaries of the Commodores' updated aero packages when they were introduced at the last round in New Zealand, the Auckland SuperSprint.

The Kiwi jumped from fourth to second on the championship, winning one race and finishing second in the other at Pukekohe in what appeared to be a changing in the guard.

Supercars experts believed the aero changes had significantly improved Holden's speed, predicting record lap…