jadnashuanh wrote: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 . 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 , 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.
 https://attachments.priuschat.com/attac ... Engine.pdf
 http://resources.mynewsdesk.com/image/u ... nioyut.pdf