Data plans in Germany that can also can be used elsewhere in Europe [duplicate]

1. There are many to choose from. You'll probably want a prepaid plan from a "discount" provider such as Simyo or Aldi Talk. Here's a comparison.
2. Typically the prepaid plan includes a pay-as-you-go rate that is very expensive (ca. 24 cents/MB), but you can add a flatrate option which will e.g. cost 9.90 EUR and give you 1GB of highspeed mobile internet within 30 days - if you use more in that time, it will still work but only at low speeds.
3. I don't know any international data plans with acceptable prices.

This situation has completely changed since the 15th of June 2017.

The EU "roam like at home" rules mean that when you use your mobile phone while travelling outside your home country in any EU country you don't have to pay any additional roaming charges. You benefit from these rules when calling (to mobile and fixed phones), sending text messages (SMS) and using data services while abroad. These rules also apply when receiving calls or texts while roaming even if the person you are calling is using a different service provider. You pay exactly the same price for using these services when travelling in the EU as you would if you were at home. In practice, your operator simply charges or takes your roaming consumption from the volumes in your domestic mobile tariff plan / bundle.

https://europa.eu/youreurope/citizens/consumers/internet-telecoms/mobile-roaming-costs/index_en.htm (some terms and conditions apply)

(I realize this is an old post recently edited by someone, but just putting it out there)