REX Miles per gallon

[PluviaPlumbum]

I was working out what split my i3 Rex had delivered Electric only to Rex and found out that it had delivered over 50 mpg based on 3 fill ups and using the rex on steady state highway cruising at @65mph. This seems to be a bonus as I was expecting around 40mpg from what I had read before committing.

Have other Rex owners seen similar figures or does the Rex MPG vary with driving situation i.e stop start traffic vs cruising?

 

[jadnashuanh]

The REx engine will operate at different speeds based on the amount of electricity the car is using at the moment. Therefore, it's really hard to state how many mile/gallon it will produce. Just like some people can drive the i3 and get nearly 6miles/kw, others driving it may have trouble getting 3.5. But, 50 miles/IMPG (40mpg US) isn't all that far off of the nominal 34MPG (US) or 42.5 imperial they achieve under specific test conditions (which you'll rarely duplicate!).

Headwinds, grade, load, temperature, how steady you drive, just like on an ICE, all affect your ultimate efficiency.

 

[BrianStanier]

I measured a fraction over 50mpg in summer weather cruising at ~65 indicated on fairly flat motorway. But the tank is so small minor filling differences have a big effect on the measurements. 50mpg I'm very happy with - not as good as the Prius, but as good as our previous ICE reserve car managed when we had the Leaf.

 

[TomMoloughney]

I've seen as low as 33mpg and as high as 45mpg, depending on how I'm driving.

 

[getakey]

I measured a fraction over 50mpg in summer weather cruising at ~65 indicated on fairly flat motorway. But the tank is so small minor filling differences have a big effect on the measurements. 50mpg I'm very happy with - not as good as the Prius, but as good as our previous ICE reserve car managed when we had the Leaf.

Prius gets >50mpg highway? I'm surprised at that. I'd be surprised with 50

 

[Jeffj]

Prius gets >50mpg highway? I'm surprised at that. I'd be surprised with 50

UK gallons are larger than US gallons...

 

[getakey]

I keep forgetting there is so much international aspect to this site

 

[jadnashuanh]

ICE motors are most efficient running at a constant speed/load only after fully warming up. It is the nature of the REx in the i3 that it may turn on and off. Depending on the conditions, it may not be running as efficiently as it could. But, to maintain the nature of the EV driving, BMW chose to turn it off when not under a big enough load (i.e., when driving slowly)