Auto makers fresh off heady sales and profits in the initial quarter are preparing for a rough ride ahead, as the global computer-chip shortage clouds an otherwise mature environment for car sales.General Motors Co. on Wednesday reported a near-record operating profit for the January-March period while competitor Ford Motor Co. a week earlier posted its best bottom line in years. Jeep-maker Stellantis NV stated that sales increased 14% for the quarter and confirmed earlier full-year guidance of 5.5% to 7.5% adjusted operating margins. It reports half-year earnings results in August.But every company stated that the shortage of semiconductors that has pushed production cuts across car factories world-wide since January will grasp production and inventories even more heading into the summer, just as American car buyers are turning out to dealerships in herds.That means car shoppers in the coming months are likely to find slimmer options and lesser deals, from new and used dealerships to the rental-car lot.