That's like saying you can't see a I6 being as efficent as a V6!
Main reason for steering clear of the I8 is it's length, have to have a bonnet that is so long, which would increase length and cost of making the car. Also effects the handling of the car and a lot of wasted engine bay space on either side.

An excellent opportunity to attach a bunch of turbos - maybe one turbo per 2 cylinders!

I had plenty of buick and packard straight eights, The best one was one I made an inlet manifold for with 8 amal TT motorcycle carbies Man it flew and ther wasn't a flathead v8 could get anywhere close to it

Sorry to be a bit off topic but speaking of weird engine combinations there was a lot of Big Block V8 front wheel drives in the US in the late 70's and early 80's.

Imagine the sound, cracking the throttle on an inline 8 with 4x DCOE webbers

AWESOME, I know all about this as iv'e had plenty of straight 8s

yes and if im not mistaken the eldorado cadillac still has a front wheel drive v8.

I think it was kenworth that had a straight 8 in the really old trucks.

There is theoretically no difference in performance between a V configuration and an inline configuration.

There are however optimal V layouts... 6 cyl = 60 dergees 8 cyl = 90 degrees

Inline is easy, V is compact... Don't see many V4's

be like the sound of 4 IDA webbers on a V8

I believe a V8 would make more power than a straight 8 due to crankshaft and camshaft weight- double on the straight 8. While a flywheel could be lighter in the Straight 8, it will be nothing in comparison to doubling a crankshaft weight.
Inline and V6's are a different story. While the crank issue remains, the firing order is rather nasty on most V6's. Ever noticed a V6 commodore that you thought was a v8 (till it revved up)? I know I have more than once and I've been around enough of each to know the difference. Most V6's have an odd firing order, so that exhaust pulses in each bank are close together- and nought can be done to fix that. On the I6 however, the 1st three and last three cylinders can be grouped together without this problem (two manifolds, like Aston Martins and Jaguars of late, also how most extractors are designed.) Thus less pulse overlap and less exhaust pressure to contend with.
Due to the number of cylinders, this isn't an issue so much on the V8, but it does give rise to that v8 rumble.

the buick V6 in the commo has an even firing order. want to see and odd fire, have a look at an old 4.3 chev V6 that is true od fire. i have semi odd fire 3.3 chev V6 in my hilux. the rod journals only have 18 degrees of offset. An even fire V6 has an offset of 30 degrees on the rod journals.

commodore V6 engines fire never fire 2 cyls on the same side of the block one after the other.

my mate has a 1930 dodge de soto with a 3.6L straight 8 and f**k yea they are huge! it doesnt have the same kinda sound as a v8 tho.. maybe it was just his zorst??