REX Acoustic sound dampening

[Goose619]

Hey guys I'm getting ready to pick up a used 2015 rex model and I 've heard some complaints about the sound of the ReX in the cabin.

I was wondering if anyone has tried lining the top cover in the trunk with some sound dampening vinyl?

Like this one: https://www.acoustimac.com/soundpro...4eBxijh8_4OOm5W8KlC2d7_DHQphO2QhoCkgAQAvD_BwE

I think it can at least cut down on the sound a bit.

 

[theothertom]

I don't think the sound is loud at all. I suggest you let the REx come on after you get your car and then decide.

 

[i3Houston]

Its not noticeable at all at freeway speeds; only at low speeds when no other cars/noises are around you can hear it.

 

[jfran2]

FWIW, my 2014 i3 Rex didn't come with a parcel shelf. I ordered one from a salvage yard, and it helped considerably with the sound. At freeway speeds, I don't hear it at all on low speed, only when it kicks into medium or high.

 

[bwilson4web]

Throw rugs?

Bob Wilson

 

[Anonymous]

Even at surface-street speeds, I can barely hear the Rex engine when it is on in my 2015. Wonder if, in the later models with the larger battery capacity, they have increased the Rex rev's, to provide more "juice" while running?

 

[jadnashuanh]

The original REx was rated at 34Hp, someone said the new one is 38, so, yes, it might very well run a bit faster on the newer ones. Note, the REx rpm is not a fixed thing, it does change with load and how far 'behind' it is in keeping the set SOC. But, it doesn't rev very high until it gets over its initial warm up period.

 

[TheMK]

The original REx was rated at 34Hp, someone said the new one is 38, so, yes, it might very well run a bit faster on the newer ones. Note, the REx rpm is not a fixed thing, it does change with load and how far 'behind' it is in keeping the set SOC. But, it doesn't rev very high until it gets over its initial warm up period.

I must preface this by saying that I have no backup/confirmation, just my own original research....

I believe that although the original REx was rated at 34Hp, somewhere down the line with an I-Step (vehicle software) update, BMW has bumped up the engine capacity in older models as well. We know that the engine it's self hasn't changed, rather the RPM at which it will run has. The original BMW i3 generates 25Kw (34HP) @ 4300 RPM [1]. Using test/measuring software (ISTA) on my i3, I have found that I can max out the REx at 4800RPM. Doing this requires a significant drop from the SoC hold point target, and also requires the vehicle to be moving quite fast. According to the W20 engine manual, the RPM isn't supposed to climb above 4300RPM but we do know that the W20 engine manual that's floating around on the internet is from the original 2014 release of the i3, and doesn't cover the upgrade. According to an i3 spec sheet dated 11/2017 [2], the output is now 38HP @ 5000RPM. I have only measured 4800RPM in my 2014, but if we look at the power and torque curves that are graphed in the W20 engine manual, we can see that the output at 4800RPM and 5000RPM is not very different at all (in fact depending on how you interpret the graph they may be identical), and both of those are certainly higher than the original 4300RPM amount.


Now the million dollar question is, was what BMW did legal? Both the 34HP, and 38HP systems are both Euro-VI compliant, so they should have no issue at all with EU emissions regulations, but what about US regulations? They might still be OK here too, the REx is rated as a SULEV here in the US, and as long as the software update version is still SULEV rated (it is, as we know from the official ratings on 2017+ models), then they should be OK here too.



[1] https://attachments.priuschat.com/attachment-files/2016/07/108943_12_W20-Engine.pdf
[2] http://resources.mynewsdesk.com/image/upload/t_attachment/vjioibvramer80nioyut.pdf

 

[panamamike]

How can I get the latest software update for the REX? I find mine to be a bit noisy, can anyone recommend a mat to help with noise reduction?

 

[jadnashuanh]

You can update things like the maps, and some of the user interface stuff yourself. Depending on the MY, maps and some other things might be done OTA.

BMW does not, generically, update people's vehicle control software unless it's a safety issue, or you complain about something not working properly, and they have a software fix for it. IOW, if you don't have a safety issue, or something deemed worthy of fixing on your vehicle, if you do want the 'latest', you'd likely have to pay for it. And, often, you may not notice anything different. On my other BMW, I needed to replace a couple of TPMS sensors. THe new ones were different enough that they also needed to do a software update. So, it just depends...

Rather than have the software built for all possible conditions and loading that bloated software onto all vehicles, BMW uses the factory configuration information and builds a specific version for your vehicle as built (or fixed, if a module has been changed since). IOW, the latest for your vehicle is likely different than that for almost anyone else as there are always running changes to modules and the option lists are also likely different.