Google crawled your site many days ago. thats why your search engine showing previous title. You can ping your site again at pingler.com.
After ping within a week your title problem will solve.

Yes its the same as you said, but it will be solved the next time that Google crawls and indexes your website again. It usually takes some days (according to the site quality and other factors that Google knows) that Google re-index a website again. Pining is a good way for informing Google about the updates of your website as another member said but its not guaranteed that Google re-index your website immediately after pining it too. Ping it and wait for some days and then your new title will be appeared on Google SERP.

Actually I have never changed my title, it has been "Super Bright LED Car Lights, LED Lights For Cars, LED Bulbs, HID Bulbs, HID Conversion Kits and Car Accessories" for at least 3 years.

In fact on Monday, when LED lights this word first landed on Page 1, it was showing my original title, but since yesterday and I checked today as well, it had changed to "LED car lights"

I suspect Google thinks you are keyword stuffing the meta. When they don't like the meta, they can substitute. I think that is what you are seeing.

Try re-submitting your sitemap.

Sometimes what Google will and can do is replace your page title with either;

1, Your most popular inbound link
2, Content it finds suitable, usually determined by links but can also be on page content.

I would go with what they have suggested, don't be too greedy with the keywords it just waters them down. I would also use your current title as the meta description.

A great tool to monitor your Google organic click-through rate is the Search Queries section of Google Webmaster Tools.

There might be possibility that you have already submitted your site into dmoz few years ago and it still it fetch the result from that. Recently I found a new tag called NOODP which allow search engine to take meta data from the current website. In dmoz there is no option to edit your information. So, to avoid fetching your data from dmoz add this tag into your site.

I do have the opt out NOODP tag in my meta already, so I am sure this is not the problem.

I changed my title, and it is now re-indexed correctly. Thanks for all the help!

Another thing about the google is: Even if my title is within 70 char, but google only show up to 50 char on SERP.

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They wont always show your full meta title, they sometimes will chose the most relevant area of the title according to the keyword/phrase searched by the user. Especially since you seperated with commas which is no good for meta titles, commas to google crawlers are a way of seperating possibilities, hence why when a full meta title does show up in serps it shows this (|) between words instead of this (,) I wouldnt worry too much about this