DETROIT — General Motors on Tuesday said the Iran war is causing cost increases to its business, but inflated consumer expenses such as higher gas prices haven't deterred buyers from spending on pricey vehicles. GM CEO Mary Barra said the Detroit automaker continues to monitor any change in customer spending but, so far, the company's vehicle mix has remained healthy. GM said it had an $52,000 average transaction price for vehicles during the first quarter, which was in line with last year. The