Do modern cars need to be warmed up before driving?
No. Idling a modern engine to warm it is a habit carried over from carburettored cars, and on a fuel-injected engine it wastes fuel, increases wear and takes longer to warm the car than simply driving it.
Carburettors metered fuel mechanically and ran badly when cold, so a car genuinely could stall or hesitate if driven off immediately. Engine management systems replaced that decades ago. A modern engine reads coolant temperature, air temperature and a dozen other inputs, and adjusts the mixture continuously. It runs correctly from the moment it starts.
Idling is in fact a poor way to warm an engine. At idle it produces very little heat, so warm-up takes several times longer than under light load. During that extended cold period the engine runs a richer mixture, and unburnt fuel washes past the piston rings and dilutes the oil film on the cylinder walls. Extended cold idling is worse for wear than gentle driving.
The practical advice is to start the engine, give it twenty to thirty seconds for oil pressure to establish and to clear the windows properly, then drive gently until the temperature gauge lifts. Avoid high revs and hard acceleration until it does — the engine is warm long before the cabin is.
Two genuine exceptions. In severe cold, well below freezing, a slightly longer idle helps oil circulate before load is applied. And you must never drive with a partly cleared windscreen, so in frost the wait is about visibility, not the engine.
Many places also restrict stationary idling, and leaving a running car unattended can invalidate insurance.