Michael Sheiman's picture

The BMW i8 is a gorgeous car, but a green one?

BMW i8 is a gorgeous car inside and out, but I can't find anything about it particularly efficient or green among hybrids, nor high performing among the competitive field of more efficient high performance EVs. It competes in a very competitive category with the Tesla Model S P85 EV on the high end and Nissan Leaf EV on the low end, both with increasingly efficient and advanced technology under their hoods that, ironically, has nothing to do with trusted internal combustion (gas) engines.

This, perhaps, explains a lot about why those cars are not getting their due respect vis-a-vis hybrids such as the BMW i8.

At a glance, the numbers and figures to declare the i8 the winner simply do not add up. The article claims "The five judges took into account the vehicles tailpipe emissions, fuel consumption, and use of a major advanced power plant technology (beyond engine componentry), aimed specifically at increasing the vehicle's environmental responsibility." So, minus powertrain innovation, which is arbitrary when/as it doesn't translate to higher "green" efficiency, it sounds to me like a contest about low carbon emissions. This holds whether such emissions occur directly (via tailpipe) or via energy/fuel use (carbon from generating the electricity used as fuel). My issue with this is, a lot of EVs easily beat the i8's figures in that emissions/"green" arena and much more.

Using the American EPA rating system.

  • Tesla Model S P85D: 87 mpge, 0-60 3.2 seconds, 0.89g's skidpad (handling ability), 4 wheel drive.
  • BMW i8: 76 mpge (and for only est. 20 miles range, so it's realistically much less unless you are only doing extremely short trips). In the case of rraveling over 20 miles, it gets only 28 mpg on gas. 0-60 4.2 seconds, 0.91g's skidpad , 4 wheel drive.
  • BMW i3: 124 mpgE, 0-60 7 seconds, 0.78g skidpad.
  • Nissan Leaf: 114 mpgE, 0-60 6.6 seconds, 0.81g skidpad.

If the test really is about emissions and fuel consumption then the i3, last year's understandable winner, achieves a whopping 124 mpge overall, making it over 1.5 times as efficient as the "green champ" i8 in all-electric mode. Also, even if the test is apparently limited to cars with very substantial revisions in 2015, the 2015 Leaf, with its heavily upgraded battery (which is definitely a vital part of the EV drivetrain) technology for 2015, gets 114 mpge, nearly the same as the BMW i3's admirable figure. In addition, the i8's optimistic mileage figures assume you aren't ever going over the i8's petty 20 mile estimated all-electric range, in which case the i8 gets much worse fuel economy (28 mpg instead of 76 mpge).

Performance wise, the Tesla Model S P85D, compared to the i8, achieves a substantially better 0-60 time, a virtually identical skidpad/handling figure, and, like the i8, the Tesla also has an intelligent 4 wheel drive system. Furthermore, it has more advanced, faster charging technology than the i8 and highly upgradable software to control all aspects of the car/drivetrain, right down to automated driving and controlling the entire car via your smartphone. Also, while the i8 flaunts its advanced use of carbon fiber for light weight, neither of its related figures of performance nor fuel economy, which you would expect to be superior due to said weight advantage, top that of the Tesla.

Go figure that I am having a very tough time seeing what the i8 has the new Tesla P85D does not.

So, how on earth did the BMW i8 win this green contest? I highly suspect this quote: "The BMW i8 gasoline hybrid looks so cool, it should be the icon for all “Green” cars." And, I agree, it's likely, for many, easily the coolest looking car of the bunch, almost like an eco-Lamborghini of sorts. I am also suspicious that the i8 may be getting brownie points for being a hybrid, combining a gas and electric motor for those with range anxiety. Then again, the Model S has about a 240 mile range- not exactly skimpy. Plus, when you do run low, the Model S has superior charging speed.

Perhaps we are supposed to assume, for your average gasoline-powered automobile drive, that mere half hour stop at a Tesla (super)charger every 200+ miles (that's generally over 3 hours straight worth of driving) is enough inconvenience to crush all its other advantages since the i8 has instant gas refueling/charging as it's a hybrid. So far as performance and emissions, though, the i8 looks like a clear sheep in wolf's clothing compared to other options; not threatening to the competition. It just happens to look very cool and be produced by a luxurious and reputable German manufacturer, but, apparently, when that shiny rubber hits the road, that is about all that stands out about it.

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Up front, I'll say I agree that the i8 is highly questionable as "green car of the year." It's exceptional in a number of ways, but not in being "green." It's green for a sports coupe, but not compared to all production cars.

That said, there are a number of things in the article I think need to be addressed.

The Tesla P85D, despite the well-publicized numbers, is not a performance car. It's great at the drag strip or on the road, but not on the track, because they still haven't addressed the heat issues. Comparing 0-60 times ignores what happens to the car around the 1 mile mark if you're pushing it. Sustained power output's much lower - about 50% of peak, a topic of much discussion on the Tesla forums.

Not that BMW i8 is a track car the way a 911 is either. BMW doesn't want to talk about the i8's Nurburgring time either, though I doubt it's 10+ minutes like the Tesla P85. (Couldn't find any data on a Nurburgring time for the P85D, though I suspect it's similar since it's more about the batteries than the electric motor output).

The EPA figures for the i8 are almost certainly wrong, because they include gas usage for the electric drive. Which means they screwed up the test, and yet recorded it as an official result anyway. They also test cars on a stationary platform and then fudge the numbers with a guesswork "correction," which means that they don't know the actual effects of wind drag. Which would be fine if all cars had the same coefficient of drag, but they don't

I don't own an i8, but I do own a Panamera S e Hybrid. EPA's stated MPGe: 50. My actual, measured MPGe: 60 city, 90 highway. EPA's stated highway MPG: 29. My actual highway MPG, once the battery is depleted: 35.

Those aren't Prius numbers or i3 numbers, and it's not anywhere near as green as either one. But don't take the EPA figures at face value, even if they're more accurate than the NEDC.

Plug-in hybrids in general do offer a different experience once you're on a road trip, even if you're talking about a Tesla with a 240 mile range and the possibility of Supercharger charging speed. The nextwork is getting better, but it's still nothing like the network of gasoline stations.

I've been on trips which were simply not possible with a Tesla because they weren't in the Supercharger network. Even inside the network, in means planning the route around then chargers, and taking more than the 5 minutes it takes to add gas. It's not 30 minutes for 200 miles, either - even if you start almost depleted for maximum charge speed, it's 130 miles in 30 minutes.

Which is great, and much better than a level-2 charger, but not something to gloss over, and not like driving 400+ miles without having to stop for fuel at all, which I've done.

Great article Michael---Pretty much what I was thinking about the i8. Looks so cool but oh so many tail pipe emissions compared to a BEV.

Having driven the BMW i8 as a press loan for four days, I can say that, hands down, it kicks the hell out of the Model S. Sure, the Tesla is just about as fast (probably a bit faster in the 0-60), but it can't sustain that kind of speed for long. Or far. The EPA's numbers for the i8 are whack. I drove it like a kid playing GTA and still managed better than 40 mpg despite that. Nevermind the complete Apples to Oranges of comparing the two cars to start with.

Finally, looking at the holistics here, the BMW i8 is far more sustainably produced and is cleaner in every point of manufacture than is the Tesla. Something that was shoved in Musk's face when he tried to belittle the i3.

Anyway, the Model S wasn't even in contention for Green Car of the Year because it wasn't "new" or "substantially new" for the 2014-15 model years.

>>"Sure, the Tesla is just about as fast (probably a bit faster in the 0-60), but it can't sustain that kind of speed for long."
>>"BMW doesn't want to talk about the i8's Nurburgring time either, though I doubt it's 10+ minutes like the Tesla P85."

Dare I admit, I have heard this complaint in several other places as well and didn't consider the use of the I8 vs. the Tesla as track cars...I was thinking more in terms of how they'd do with IMO more everyday (and street legal) driving maneuvers such as quick freeway passing or pulling ahead of traffic from a stop light, for example. It makes sense the i8 would be more stable for prolonged performance driving as Tesla's automation focuses somewhat on range and the Tesla has reported heat issues when driven as such.

>>"They also test cars on a stationary platform and then fudge the numbers with a guesswork "correction," which means that they don't know the actual effects of wind drag. Which would be fine if all cars had the same coefficient of drag, but they don't".

Oddly enough, I've read 0.24 cd for the Tesla and 0.28 for the IMO sleeker looking BMW. I am guessing the discrepancy is due to the Tesla's smooth underbody. Granted, the i8 could have a lower surface area, but I doubt it would cancel out the effect of the Tesla's lower cd.

>>"the BMW i8 is far more sustainably produced and is cleaner in every point of manufacture than is the Tesla. Something that was shoved in Musk's face when he tried to belittle the i3. "

I find it odd the original article on the i8 winning "Green Car of the Year" does not mention this, but focuses on drivetrain innovations. It's definitely a significant factor in how green the car is that both I and apparently the original article missed.

Shortly, I agree on the Tesla's lack of track performance and/or prolonged hard driving (due to issues such as overheating and automation limiting power for range optimization)...although I assumed that's not what the average (or legal) driver would use it for.

Far as the cd figures rendering inaccurate EPA mpg ratings in favor of the Tesla, it makes sense except for the odd fact the Tesla has a lower cd than the sleek i8, thanks largely to its smooth/aerodynamic underbody.

I can't help but comment. I admit it upfront: I own an i8, so I may be biased. But I opted for the i8 against the Tesla after having driven both extensively. There is so much wrong with this article, I don't even know where to start. So random pick:

A) Skid pad numbers. Have you actually done one of those yourself? Have you experienced the difference in cornering speed between .89 and .91? Secondly, skid pad is NOT a measure of handling ability. It measures cornering grip and says nothing about load shifts when you have to change direction.

B) After over 5500 miles in my i8, I'm getting 76 mpg (US) average. I have the app data to back it up. Not green?

C) Range anxiety in the Tesla is conveniently downplayed. The Tesla does not have a 240 mile range if you go fast (see below). If you go on a long drive, even if you go along a route that has Superchargers, you still need to stop every 150 or so miles (depending on now fast you're going - Oh wait, it doesn't want to go fast for long) for 45 minutes to get an 80% charge, which means you'll get only 120 miles. In the end, that makes you slower than a scooter.

D) Some people do live in countries where you can go fast. The Tesla is quick off the mark, but famously loses steam beyond 90 mph or so. NOT a performance car, despite the power claims. Typical American car building philosophy.

E) the word 'apparently' in the last sentence is a give-away. The author doesn't have a clue. The whole article is hearsay. Not enough to threaten the competition? There is no real competition. The Tesla is a family saloon with a bit of straight line performance at lower speed, but lets you down on long trips or spirited drives. Compare it to a 6-series GT if you want. The 911 is in a different category as well. Much more of a driver's car, but you have to push it to get economy. I've owned Porsches for years. Love them. But the i8 is an entirely new breed. And that's why it deserves the attention it gets.