If you are driving your car and your timing belt broke, results can be both dangerous and costly. Car Timing belt advised replacement intervals can improve your engine life & save hundreds of dollars too.
Timing belt cost is not so high to avoid replace. If you can hear noise and observed bad timing belt symptoms. Driver must not delay it. Serpentine belt is different from drive belt, You can still drive with broken serpentine but driving with bad drive belt can be dangerous in the way
In an interference engine, If your engine is on and if it breaks, It will stuck on different parts of engine. Because it is driven by crankshaft and operating camshaft. It shall stop one or both of them. Sometimes you may need to rebuild engine too. Car can sudden stop at highways.
In non-interference engine, you will not face any loss with breaking of other engine internal parts. Subaru & some other diesel engines are non-interference. Always consult your mechanic about your engine.