XSeries-forum

So liking the look of both and accepting the fuel will be terrible im stuck the pros and cons of each.

Having had a 4.8 before I know all about the fun of the air suspension, gearbox harsh shifts and valve stem seals however ive also heard the the 4.6 has the timing chain issue and heard of a few with bottom end failure !

Externally the 4.8 has the more modern front end but what else does it get over the 4.6 and if you had to chose what would you go hinting for and why ?

You have summed up pros and cons of each pretty well. 

The obvious difference will potentially be price with examples of clean 4.6is being circa 4k and upwards whereas a 4.8is will typically cost 2k or so more. There are exceptions and the reality for used sellers of all used E53's is they may need to be realistic if basically selling a relatively complex used car as sold as seen.

More traders now try to fob off used E53 buyers by careful wording effectively indicating that they won't entertain sorting post sale issues.....rather naughty if they are asking all the money which is the norm & arguably in breach of consumer law.

4.8is also has potential for pan roof issues but has xdrive & slightly better mpg. If optioned the heated Steering wheel is a nice luxury if you leave it outside in cold of winter. It will warm your hands after you snap your frozen drivers door handle carrier  . Also bear in mind valley pan coolant pipe seal can fail on 4.8is....a big labour bill.

Both are capable of producing large repair bills even with impeccable history.

The more things fixed in prior ownership the less should go wrong but even the most pampered cars can payback owners with more or similar issues.

Have seriously looked at examples of both 4.6is & 4.8is. I came close to a 4.8is with 59k miles, fsh and rolling bmw extended warranty (cheaper to renew if sourced sub 60k and and kept up). Number of reasons why I didn't go for it not least the cost of keeping up history at main dealer.

I owned a well maintained prefacelift 4.4i that robbed my wallet in repairs and I know another members has a pampered 4.8is that has often has warranty work done.

I recently posted elsewhere re a 1 owner 4.6is I viewed that likely needed a 2k spend to sort.....much of which I discovered when under the car on my ramps.

Annoying when one keeps on top of things only to get another issue.

Maths aside it can be quite irritating when a car has mutual repair needs in between servicing...Oddly I still miss my old 4.4i some months on since sold on.

Do bear in mind that historic neglect from being driven on low oil levels might contribute to engine issues you mentioned. The bottom end failures on 4.6is probably not as common as feared by reading up online.

I keep an eye out for both 4.6is & 4.8is in classifieds but trouble is I know enough to warn myself away from most that are advertised.

Having now been an X owner for 2.5 years, I know, 5 minutes in comparison to some, I am happy with the choice I made. It now has 134k and my intention is to change the timing chain guides at 150k needed or not, assuming I get there without issue. I like the springs and strut setup, simple, cheap (relative to air struts) reliable. Don't think guides are any more expensive than valve seals which both are reported  as weak areas. Quite possible bottom end failures are due to guides failing and bits getting sucked into the oil pump. 4.6l I would say has a more reliable drive train, less prone to differences in tyre wear issues. Rear air is pretty simple and seems to be problem free. Gearbox is not really reported as failing that often but we're into an area of it costing half the worth of the whole vehicle. Having read on here and other forums I'm sure a lot of both boxes have been replaced due to a want of a temperature sensor or some other cheap fix. I liked the idea of the last of the M62's, should be as good as it gets. ( I now have a mental picture of going to my X in the morning, wheels have fallen off, bonnet open, steam pouring out, fire just started behind dash ) Back to reality, brakes seem to last for ever. Power isn't an issue, less than 10 between the two. Of course, not having owned a 4.8l I am biased towards the 4.6l, much more rare. I like the older stuff, my newest car, the VW R32 is 14 and interestingly my oldest car is worth the most at 65k.  I think either will make you smile again.

I wouldn't worry about 4.6 bottom ends, mine only failed because the 'expert' independent garage didn't remove all of the debris after cam tensioner failure, resulting in a blocked oil pump suction strainer.

Hi

Both the 4.6 and the 4.8 are nice to have, I think find the best example you can and buy that even as good examples are getting harder to come by, unless there is a specific option one has for you. I ended up with a 4.4 as I couldn't find a good enough 4.8 and change the bumpers so it was similar to the 4.8.

For me the 4.6 has a smaller. Sunroof and does not have the probs of the facelift 4.8 panoramic roof.

I like the front bumper on the 4.8i more but yesterday I prefer the 5spoke 20" wheels of the 4.6.

The advantage with both is the bits are similar and wheels can be stopped etc but look for one with good maintenance as that is key with these cars

Graeme

There is certainly the price difference but I think these are starting to be one of those cars you buy and understand you will get stuck in it a tad tbh so I can deal with the odd issue at the right price aslong as its not terminal !

I think id like to see some proof of one of the big issues having been done (timing chain, stem seals, gearbox, air ecu).

Warranty on these seems to be getting expensice now - I was quoted close to a grand on my previous 4.8 !

Has anyone driven both able to rate the difference in comfort and experience between the air suspension and gearbox setups ?

Im certainly a "fix my own" stuff and the only thing I think id avoid doing myself would be the gearbox. I also seem to prefer the looks of older stuff (boxes on wheels rather than curves etc).

The front end of the 4.8 and the wheels do it for me but also the M62 and the 5 spokes are good too hence why im stuck 

For me its simple: 4.8is, better engine, better 4x4 system (xdrive), better gearbox ( 6 speed ), much fresher, sharp front end...