Quote:
Originally Posted by tooloud10
Seems like I get 28mpg pretty regularly on my 45e even with the EV battery at —, but it’s odd to me that the EPA rating is only 19/22.
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I don't think BMW ever claim 45e is 19/22. I have only see 52MPGe and 20MPG combined after usable HVB is depleted. I think it is not too far from reality. In my experience, combine MPG when I don't charge HVB at all, it is 22MPG.
Quote:
Originally Posted by tooloud10
Right, but makes me wonder why the ‘official’ figures are so low—in fact, lower than the standard 40i model.
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This can easily be explained. 20MPG after HVB depleted vs 22MPG from 40i. First is 40i is 800lb lighter. When non Plug in HEV is better than same ICE is because non P Hybrid only need 1-2kWh of HVB. For example, Highlander hybrid only carry 1.9kWh. 45e carries 24kWh. If you don't charge the car, most of these 24kWh is just dead weight. Hybrid's main advantage is stop and go traffic. Here 800lb sure make a impact. Second is 40i gears advantage. On highway, 40i will run at lower RPM than 45e. So both ends give advantage to 40i.
I have a table posted somewhere, but quick calculation. At the same highway speed, where both will be at 8th gear. 45e needs to spin ICE at 2425 RPM, 40i only need to speed at 2166. Difference is 15%. Speed at this RPM should be ~71.5MPH. My math may be off. But gear ratio numbers are from BMW