with today's cars, close tolerances between the piston and the cylinder bore, close tolerance between the crankshaft and camshaft bearings, there is no need to warm the engine up. the radiators of yesteryears had three rows of cooling tube versus today's with only one does not need the traditional warmup. it was so designed to save fuel and increase the mpg rating of the car. even the oxygen sensors have shorter time to get to closed loop because of the heating element inside the oxygen sensor itself. parts have been lightened (again for fuel economy) and gets to operating temperature faster. with some purely air cooled engines, the moment the engine runs, it is as warm as operating temperature. the problem though, with the designed short to no warm up time needed, is that the engine overheats if the cooling system is not properly operating: i.e. no thermostat or stuck closed thermostat, radiator cap that can not reach the required pressure, wrong type or wrong mixture of the anti freeze coolant, insufficient airflow to the radiator, air pockets in the cooling system that had not been bled, over advanced ignition timing, clogged exhaust system and vacuum leak at the intake manifold. today's car are made to be driven as soon as the engine starts.