Which engine do I actually have ...
 

... or is there actually a difference in these two?

If I go to realOEM.com and plug in my VIN, I get this:

Attachment 64264

But when I go to various sites, such as amazon or ebay and look at accessories/parts, there are two engines to choose from:

Attachment 64265

How do I find out which one I have?

I think the second option.

Well I don't go on Amazon for parts hunting first of all,

A quick Wikipedia search finds that you have the N62B48, as opposed to the 4.4L N62B44

N62B484.8 L (4799 cc/292 in³)265 kW (360 hp) @ 6200500 N·m (369 lb·ft) @ 350065002004270 kW (367 hp) @ 6300490 N·m (361 lb·ft) @ 34006500



Hope that answers your question

If you calculate displacement from published bore and stroke, you get 4799. That is what my reference say the N62B48 4.8 displaces.

There was only one 4.8 engine in the x5.

Not sure what the other figure is, but it demonstrates that you shouldn't believe everything you read on internet sites.

Edit:

Here is a theory for what the 4837 cc displacement figure represents:

The stroke of the X5 engine is 88.3 mm. When Alpina built their 4.8 they said the stroke was 89 mm (even though they got the crank from BMW). 89 mm stroke gives you 4837 cc displacement. Now, was it really 89, or did they round up?

i usually go with 4799 option, but to be honest, i do not know why they list two engines... the 4.8 N62 is also used in the 5 and 7 series, and in the E70 X5, but it is not the exactly the same as the N62 in the 4.8is...

so, i'd like to see if there is an answer to this question too...

:)

Sometimes I'll just run a quick search and, while I'd probably never order anything via amazon, it can at least give me a ballpark price to keep in my head while prioritizing what projects I'm going to tackle first, or what to expect down the road.

I guess that kind of answers my question, even though I don't understand any of it. :) I'm not much of a car guy...but I am hoping to learn. I mean, I like cars, I've always enjoyed having a nice one that looks good and is fun to drive. But I'm just now wanting to start learning to DIY some of my own maintenance/repairs.

I've been fixing appliances around the house lately with the help of forums and youtube, and I'm realizing a lot of it is not too difficult, which makes me want to learn more.

Thanks!