Any real limit to running REX?

[alohart]

It’s an app available on Apple

The mi3 app is iOS-only. The Android-only "electrified" app has similar functionality.

 

[SteveinParadise]

Just of interest what is im3 rex runtime readings all of your i3 rex's? We have a 2016 with 104K Km (65K Mi) on the clock and the rex has done 11k km (6.8k mi) on the clock. does BMW have a basic expected runtime on the rex? What's the highest anyone has reported on their Rex?

 

[aapl]

I've driven for 600+ miles in one day with 550 miles of it on the rex, I added an extra fuel tank so my rex range is roughly 250 miles.

I did need to stop for gas, but other than that it's gone just fine. It keeps up pretty well as long as you're not going 70+ the entire time. I would turn it on at 75% and leave it until I was within 50 miles of home and use the battery for the last bit of my trip.

You can drive on the rex so long as you have fuel.

Can you give us details on your extra fuel tank?

 

[JohnnyCakes]

Can you give us details on your extra fuel tank?

People install tanks in the frunk. Done right, they don't throw codes but require some pretty sophisticated mods with proper venting, pumps, hose etc. There's also a contingent that just puts a fuel can in the frunk.

That said, you will get a huge reaction from posters here. Most say "frunk is a crumple zone, you are asking for a fire" and other say, "nah, no problem." I'm in the "not worth the risk" category.

This dude showed that if the gas station is on the exit ramp (or you hit a green light), from leaving highway to re-entering highway after fill-up is two minutes. And he wasn't trying for a NASCAR or Formula One stop, he just kinda sauntered.

 

[robthebold]

People install tanks them in the frunk. Done right, they don't throw codes but require some pretty sophisticated mods with proper venting, pumps, hose etc. There's also a contingent that just puts a fuel can in the frunk.

That said, you will get a huge reaction from posters here. Most say "frunk is not a crumple zone, you are asking for a fire" and other say, "nah, no problem." I'm in the "not worth the risk" category.

This dude showed that if the gas station is on the exit ramp (or you hit a green light), from leaving highway to re-entering highway after fill-up is two minutes. And he wasn't trying for a NASCAR or Formula One stop, he just kinda sauntered.

". . . PLEASE PREPAY BEFORE PUMPING" . . . nice . . .

 

[Christopher Guay]

Because of the way that the REx is decoupled from the wheels, it seems unlikely that its total use could be expressed in miles. There are situations where the petrol engine contributes only part of the energy while driving (i.e. the battery is still discharging, even with input from the REx) and there will be others where it contributes more.

So I suspect that the best you could hope for is the total runtime of the engine. In theory the total number of revolutions could be logged, but I doubt they bother.

If the rest of the "driver experience" is anything to go by, it's unlikely that BMW would have made this data visible to the owner anywhere, so you would probably need a diagnostic tool such as BimmerLink to access the data, if it's available at all.

They should show " runtime" of the engine, like a commercial tractor. ( I think you can show it on a obd reader)

 

[Mustrum Ridcully]

The REX and its fuel system didn't like it. When i switched to Shell ethanol-free fuel, I didn't have a problem from this moment. Now it is no more available since a few months,

You can go to a small airport and buy 100ll (low lead) they don't allow corn lcker in aviation fuel yet. Good stuff for small engines that sit a lot like lawnmowers in the great white North

 

[Mr. Mindless]

Leaded fuel will hurt catalytic converters and oxygen sensors, so I wouldn’t suggest that for the rex engine…

 

[Mustrum Ridcully]

Oh okay I thought the Rex was just a small 600cc scooter engine tuned to run at a constant rpm to suit the generator.

 

[Mr. Mindless]

It is, but in a car with efi it’ll absolutely still have the sensors, and I’m sure the emissions control equipment too.

 

[nickp]

The Rex should have a lot of longevity. It's a robust scooter engine and in the I3 it's really not connected to the drive train but only acts as a generator.

 

[RhodyDave]

They do an emissions test on mine every two years! And yes it has a cat converter, too.

 

[B. Driest]

+1 - Can you give us details on your extra fuel tank?

 

[Sd2649]

I've driven for 600+ miles in one day with 550 miles of it on the rex, I added an extra fuel tank so my rex range is roughly 250 miles.

I did need to stop for gas, but other than that it's gone just fine. It keeps up pretty well as long as you're not going 70+ the entire time. I would turn it on at 75% and leave it until I was within 50 miles of home and use the battery for the last bit of my trip.

You can drive on the rex so long as you have fuel.

Can you tell how you added the extra fuel?

 

[archiegoodwin]

Congratulations on buying the i3Rex at a bargain price! I wish I had waited. I bought mine used around 25 months ago for USD39k from a dealer in Los Angeles who was so upset that I turned down financing and warranty that he refuses to give me a ride back to the airport. I was not allowed to buy it over the internet and was told to fly there to look at the car. I still wonder what I was supposed to see. This is an interesting discussion. I have deployed the Rex once (I was surprised that some very upscale towns lacked charging stations) and will try to do it more often.

 

[alohart]

I bought mine used around 25 months ago for USD39k from a dealer in Los Angeles who was so upset that I turned down financing and warranty that he refuses to give me a ride back to the airport. I was not allowed to buy it over the internet and was told to fly there to look at the car.

You bought your i3 when they were in high demand and were priced accordingly as I did. However, I also sold an i3 during that period for a good price, so it was the price differential that mattered to me. I, too, was unable to buy an i3 remotely from a West Coast BMW dealer because they really didn't want to deal with an out-of-state buyer when they felt that they could sell their used i3's to a local buyer fairly quickly. I hope that yours is a 2021 REx for what you paid.

 

[Simone Mogul]

You bought your i3 when they were in high demand and were priced accordingly as I did. However, I also sold an i3 during that period for a good price, so it was the price differential that mattered to me. I, too, was unable to buy an i3 remotely from a West Coast BMW dealer because they really didn't want to deal with an out-of-state buyer when they felt that they could sell their used i3's to a local buyer fairly quickly. I hope that yours is a 2021 REx for what you paid.

I’m in the process of buying a 2021 Rex and having it shipped. I had a third party company (POM) inspect it. They did not do a through job. The inspector came with out a OBD. He did test drive it. And it still is under the original warranty till the end of April
It has some dings and needs a new windshield and getting new tires I’ll probably need a new 12v battery. I’ll see when it arrives.

 

[JohnnyCakes]

I have deployed the Rex once (I was surprised that some very upscale towns lacked charging stations) and will try to do it more often.

Having a Rex is the joy of never stressing that a charging station is crowded, broken, or non-existent. The BEV drivers are adamant that REx is a waste of money, but I'll take the relaxing approach every time.

 

[DinViesel]

I drove my 2019 S Rex from Los Angeles to Austin using the REX almost exclusively. Yes I used the 2 gas cans in the frunk and I only stopped to fill them and the main tank up. The REX is genius and anyone who says otherwise is jealous (IMO). There are literally zero downsides to having it and only pluses. I’ve heard some complain it’s add to much weight, others say it’s noisy and some actually say the maintenance is too much. Talk about grasping at straws…

 

[mojo]

The strongest case that I've heard from others is that complexity is the enemy of reliability, and there is absolutely no doubt that the REx is more complex than the BEV.

In reality, whether BEV or REx suits you better depends on your circumstances and, to an extent, your location. I've owned my 120Ah BEV for more than 18 months now, and I've never had a situation where I would have needed to use the REx engine - so for my circumstances it would simply be a waste - weight carried around everywhere without any useful purpose.

And in the UK it's not quite as simple as it seems in the US, because the REx models were only available here with the 60 and 94Ah battery sizes - so here you have to make a compromise on battery capacity and vehicle age if you want a REx.

So, overall, it's not people grasping at straws - there are actually genuine reasons why people make the choices that they do.