I am using an android car stereo for a year now and here I am sharing the experience with you.
Nowadays, in the Indian market, I can see that Android car stereo starts from 1GB RAM. Honestly, 1GB RAM is enough if the manufacturer does not give the option to install the apps from "Play store". But since, we can install apps from "Play store", you will find that your car stereo is laggy, even with 2GB RAM.
Following issues you will face because of not enough RAM
Another big issue with Android car stereos is, the manufacturer uses Android OS but the manufacturer does not provide any updates. Many software related issues can be resolved from updates.
Most of the Android car stereo does not provide any support to Apple devices. Some manufacturer provides support with additional hardware which comes with additional cost. In short, if you are an iPhone user, you will not have a good experience with Android stereo.
Final Verdict: There are some manufacturers in the international market who have overcome the above issues. I will recommend, go for "Sony", "Pioneer" or "Kenwood" for the best experiences.