Spotlight (in Yosemite) has the ability to search the web. However, this only works with Bing. Is it possible to switch it to using Google?
It is not possible to get suggestions from Google, but it is possible to do a Google (or any other supported search engines) search from Spotlight.
Select your favorite search engine in the Safari preferences. Then in spotlight you type the term to be searched and then do the search with ⌘ + B.
This works even if your default browser is not Safari, but will use Safari's default search engine.
In OS X 10.10 someone has made a spotlight plugin which has unofficially reversed engineered the API necessary to add new search engines. i.e. google. The project is called flashlight. It comes out of the box with a lot of plugins, including google. To use it, you start spotlight and enter g yosemite, for example, which does a google search for "yosemite"
This open-source app is hosted on git hub and has releases which mean you just install the .app file, as usual. However, it's not signed so you may need to go to system preferences -> security & privacy and choose to allow the app to open (which you do after starting it and getting the error message that the app is not from the app store). Assuming you trust the app and/or my recommendation. You may like to visit the github site and see how many people have starred this application, to give you some sense of confidence. download here: http://flashlight.nateparrott.com/
You might check out Google Quick Search Box. From their description:
Quick Search Box is an open source search box that allows you to search data on your computer and across the web. With Quick Search Box you can search for information from just about anywhere. You can then perform actions on the search results, such as launching applications, emailing friends, or playing a song.
Otherwise, OS X Yosemite still has a shortcut in
System Preferences >>
Shortcuts >> Under
Search with Google
However, the short answer to your question is no. You cannot use spotlight to directly search Google.
If you want to search more than google, an interesting alternative is Alfred, it's pretty close to spotlight, but has a lot more options (especially if you buy the power pack.
Open Safari, open preferences > search > Make sure your search engine is set to Google. Also, make sure to include Spotlight Suggestions. This should do the trick. I have attached my settings, which allow me to use Google with Spotlight. If you need more help, comment and I'll be interested to help! My settings: