Low interest rates and cheap petrol are driving strong interest in the Boxing Day sales.

Mall car parks around Auckland were full to overflowing on the first day, with reports of people leaving their cars on grass berms in the rush for a bargain.

But retail expert Diane Wehrl says shops are waking up to the fact some people prefer to spend from home.

"Increasingly, online is encroaching into bricks and mortar stores, but retailers actually do embrace online shopping as part of their overall proposition."