Why it's time to get over your EV range anxiety [Arstechnica]

I was looking at InsideEVs' Real World Highway Range Of Today's Electric Cars, and noticed what appears to be an anomaly between their results and the EPA's ranges for pre- and post-LCI MINI Cooper SEs.



Note: I deleted from the InsideEVs list any EV that isn't as much fun to drive as a MINI Cooper SE. I also inserted the EPA's range estimates. Of course, the EPA tests are not just driving at 70 mph until the battery runs out, but I'm surprised the more aerodynamic post-LCI SE doesn't also best the pre-LCI SE on the e-way.

 

The 2022+ test used Hankook summer tires (guessing it's the same press car as Munro Live hoist review) and tentacle spoke rims and the pre-LCI used the "corona" wheels + Goodyear summer tires. Also the last 7 miles (5mi actually driven) of the 2020 was driven around the parking lot.

 

Based on the variation in range people in this forum report I'm inclined to believe the wheels make a huge difference, particularly at higher speeds. It's almost unfortunate that MINI offers so many wheel styles, it would be a Herculean task to do range tests with every style. I think it's safe to say the Power Spoke and Spectre Grey Revolites are the most efficient, since those are the default wheels MINI provides.

 

Honestly pick whichever wheel/tire combination brings you joy. I'm done with the hypermiling experiments and hopefully V2G will be available for the next generation.

I'm going to milk the free DCFC and resell the energy back to the grid.

 

Totally agree with this, but for "scientific" comparisons there should be some control of the variables.

 

... including, in this case, not only the wheels and tires, but the mileage on the latter as well.

Even then, there's quite possibly enough variation in the environmental conditions, actual capacity of the batteries, etc., to make such real-world comparisons extremely challenging, even if you swap wheels and tires between vehicles.

 

When will the EPA come out with a SPM (or is it SPkW) test? That will knock a few cars of peoples long list.





(smiles per mile)

 

So I was bored and haven't burdened everyone with maths for a while, so...... To put the issue to rest, here are some plots for various cars - 2 for the MINI which show what weight and Cd do. Efficiency when cruising is > 95% so I ignored that. All cars have similar tyres at 0.015 rolling resistance, and a hotel load (accessories) of 2kW. The fourth trace is a MINI with only 1.5kW for demonstration purposes. The X axis is m/s, so we go to about 150kph. It is surprisingly accurate when comparing to published figures, and my own records. So what does it show? The Volvo isn't much bigger in area (mini = 2.1, tesla = 2.22, volvo = 2.3) and has similar Cd to the MINI (0.319 vs 0.3) but much worse than the tesla (0.23). The wieghts are 1365kg for the MINI, 1730 for the Tesla and 2154 for the volvo. Each has an 85kg passenger (person plus luggage).

So what do we see. The MINI (purple) is the most efficient until almost 100kph. The volvo is always around 5kWh/100km above the mini, and the tesla is about 1.5 above at slow speeds, but catches up as the speed increases. The bottom (green) line is the MINI with only 1.5kW accessories. This shows that weight and accessory load is king at slow speed, and drag takes over at higher speed. It must be noted, that air friction isn't as important as most people would suggest. The weight (ie volvo vs MINI) is the biggest difference. Incidentally, this graph is pretty accurate according to reported stats for all three cars (good guesses).

So around town, weight and accessories (aircon/heater) is what determines efficiency, and drag really only comes into play at high speeds. Incidentally, the MINI and Tesla cross at almost exactly 100kph. So under 100kph, the MINI is more efficient, at over 100kph, the Tesla is. Oh, I assumed 1.2kg/m^3 for air density which is about right for 25C and standard 1ATM. Cooler air is more dense, so the air friction will increase by about 10% with a 27C drop.

Still with me (not asleep)? Enjoy....

 

So I was bored and haven't burdened everyone with maths for a while, so...... To put the issue to rest, here are some plots for various cars - 2 for the MINI which show what weight and Cd do. Efficiency when cruising is > 95% so I ignored that. All cars have similar tyres at 0.015 rolling resistance, and a hotel load (accessories) of 2kW. The fourth trace is a MINI with only 1.5kW for demonstration purposes. The X axis is m/s, so we go to about 150kph. It is surprisingly accurate when comparing to published figures, and my own records. So what does it show? The Volvo isn't much bigger in area (mini = 2.1, tesla = 2.22, volvo = 2.5) and has similar Cd to the MINI (0.319 vs 0.3) but much worse than the tesla (0.23). The wieghts are 1365kg for the MINI, 1730 for the Tesla and 2154 for the volvo. Each has an 85kg passenger (person plus luggage).

So what do we see. The MINI (purple) is the most efficient until almost 100kph. The volvo is always around 5kWh/100km above the mini, and the tesla is about 1.5 above at slow speeds, but catches up as the speed increases. The bottom (green) line is the MINI with only 1.5kW accessories. This shows that weight and accessory load is king at slow speed, and drag takes over at higher speed. It must be noted, that air friction isn't as important as most people would suggest. The weight (ie volvo vs MINI) is the biggest difference. Incidentally, this graph is pretty accurate according to reported stats for all three cars (good guesses).

So around town, weight and accessories (aircon/heater) is what determines efficiency, and drag really only comes into play at high speeds. Incidentally, the MINI and Tesla cross at almost exactly 100kph. So under 100kph, the MINI is more efficient, at over 100kph, the Tesla is. Oh, I assumed 1.2kg/m^3 for air density which is about right for 25C and standard 1ATM. Cooler air is more dense, so the air friction will increase by about 10% with a 27C drop.

Still with me (not asleep)? Enjoy....

 

I noticed my mi/kWh take a huge hit when I'm on the freeway driving >70mph (about 2.5 mi/kWh); whereas, in city streets, I average around 4.5 mi/kWh. Always figured it's the drag as a result of the body shape.

 

I generally take their testing as a good estimation of real world range, but my results in the Mini at 70mph amount to just over 130 miles of range so other than the fact we have 16” victory wheels and no sunroof (base signature trim) I don’t understand why there is such a discrepancy with what they’re getting. IIRC I was getting 114 even at freezing temperatures so something is off…

 

I agree with ghost - over 70 is terrible and 50-55 is much better. Accordingly, I stick to back roads as much as possible.

 

I relinked it earlier in this thread but that seems like an analytical version of the EPAs published test data for road load coefficients I posted a while ago (here). They don't account for the "hotel" load so I think that's what is responsible for the initial downward slope of your graph?

From the EPA data, the MINI has one of the lowest total drag values at low speeds (beaten only by the Leaf and Ioniq 5 RWD) but the Model 3 surpasses it at 25mph (vs your 100kph/62mph). The heavy Lucid beats the MINI at just 15mph.

Another notable difference is the AWD vs RWD Ioniq. Unclear if it's just the front motor causing all that extra drag or if there's some other difference like tires.

 

I think the standard range RWD IONIQ 5 58kWh is like 3,968 lbs and the fully loaded IONIQ 5 AWD 77.4kWh is 5,000 lbs.