[MENTION=7]IDAFC21[/MENTION]
How often are the alien energy cells around? I only see them rarely on the map. Not every day.
They only show up at night, so as long as its dark out, they should be out. It helps if you change your map to only show the alien cells, that way theres no other junk getting in the way on the map. I found them all now, but I did have to use a guide to find the last few. I think they only show up on the map once you drive near them.
And I don't know how far along you are, but you eventually unlock alien plants as well, and those only show up when its raining. I haven't got all of those yet.
Im on the final build for my house, but you pretty much have to complete EVERY challenge to get enough bricks to unlock it. Still haven't gotten my lego barn find car, even tho I found the barn ages ago, but I have a feeling Forza is waiting until Lego releases the real thing, and I don't think that's coming out until August 1st.....