I've done podcasting and audio recording for a while in my past, and learned quickly that it's not simply a matter of just reading the text off the page. You have to have a good presence, know how to project your voice, know how to breathe from your diaphragm, etc., etc., etc.
Assuming you know all that, you also need to know whether your voice is one someone would want
in their ear for hours on end. An average audiobook is anywhere between 8 and 15 hours. For the Game of Thrones - now you're talking about 30-40 hours! That's a lot of time to be in someone's head, so you better sound wonderful! This is why there's such a thing as voice over talent.
Ever notice that in animated cartoons, TV commercials, and even podcasts, certain voices resonate much better than others? It's because people have trained on how to present their voices. This is why some people are famous for their voice. Probably one of the best known examples of these is James Earl Jones. He's the legendary voice behind Darth Vader, the announcement for CNN, and much more. You instantly know it's him.
I work in telecommunications and even telephone companies hire voice over talent for their automated attendant greetings, and other pre-recorded stuff like "All Circuits are busy now". They easily pay in the thousands of dollars for 30 seconds of audio because it's
professional quality audio.
So, let's assume for a minute that you are one of the lucky ones whose voice was made to be recorded. You are the radio DJ. You are the aspiring actor. You are the next voice of Kraft Macaroni and Cheese (you know you love it!). Now, you need to be able to:
1. Know how to read a script
2. Have the equipment to record your voice (don't use just a laptop built in mic - use a condenser mic like a
Yeti snowball or a
Samson).*
3. Have the dedicated space to set up a permanent work station for recording (monitor, laptop, mic, boom, filter, soundproofing, etc.).
4. Have the software to edit and normalize your voice work and splice segments together. You may also need to output into several formats such as mp3, AAC, m4p, OOG, and more, depending on who is doing the distributing.**
Now, to answer your original question - where to record...
If you don't have a dedicated space - you want some area where sound can't echo. A car would work, as would a closet with some clothes in there. Ideally though, it's a small room with sound proofing bubbles or foam installed. This way you can produce consistent results repeatedly. (Unless you plan on recording all 8-15 hours of an audiobook at once - good luck with that by the way...)
ETA:
*I own the Samson USB condenser mic and have a dedicated mic stand along with the pop filter. You could use a condenser mic that has a preamp, which gives you more control over the quality of audio, but I quickly grew tired of having to dial that in and out when I was first starting out. Additionally, the quality of the XLR cables for an older style mic to preamp will play a huge role in the resulting quality of audio, and at the end of the day a USB condenser microphone will produce similar audio quality for half the price, and a lot less hassle in the long run.
**Side note on software. Yes, you can use open source software like Audacity, but you'll get more bang for your buck with something like Adobe Audition, Pro Tools, or Cubase.