Stupid Question: How does multiple domains on one website work for SEO?

Here is a stupid question.

Lets say I have a huge side about : "hybrid cars" located at hybridcars.com.

Now to compliment my website and get more traffic, I also register the domain: gas efficient cars.com and point it to hybridcars.com

Will google index the website as both gasefficientcars.com and hybridcars.com? How does it show in search results?

If this is good for SEO, what is the proper way to link the domains and website so that google gets happy?

 

I had a somewhat simillar question last time here:
forums.digitalpoint.com/showthread.php?t=1714592

 

make website sub domains or redirect all site on one site

 

the answer to your question is, google will index hybridcars.com only.

 

google will index only your first site.

 

use linkwell method,and link the center of the linkwell to your main site.., use Web 2.0 to form a whell that link to your main site, this is deadly mate

 

a similar question. which is a better solution for SEO?

redirect

sub.domain.com to domain.com/sub

or

domain.com/sub to sub.domain.com?

 

What about backlinks on different domains but on the same server?

 

Ensure you use a 301 redirect for the gasefficientcars.com domain otherwise you could end up with some duplicate content issues, and yes, Google will only pay real attention to the original domain with the content.

 

what i have read, if domain names host on the same ip (shared server), the backlinks will not be as effective as from another IP.