Re: 8 Speed for the 2013 model
What I have found with any gearbox that has over 5 gears is they tend to hunt a lot.
While it can bring better fuel economy, running a motor out of it's ideal powerband will result in worse fuel economy.
The 5 speed Merc box that comes in the CRD and V6 is a great box. Very strong and seems to have the right ratios when required. Having my CRD tick over at just under 2,000rpm @ 100km/h is about ideal for both power and economy. Additional ratios will only give marginal improvements in economy, however I would rather have an old proven gearbox that has sat behind many more powerful motors, than some untested 7+ speed box that is yet to be proven.
While it would be nice to keep up with Merc's 7sp, I really do not think it is a major factor.
Previous Ride = 2011 JGC CRD Overland
Current Ride = 2014 Silver JGC SRT
with Pano, HK and Spider monkeys.
Mods = CLSTech Ribbon Mod
Best 1/4 13.4@102Mph