Just over a week ago I drove the 2012 Fisker Karma around our semi-official One Lap of Orange County city fuel economy course. Aside from our 2011 Chevrolet Volt, the Fisker is the only other plug-in hybrid on the market. But our Chevrolet Volt has never taken a trip around the OLOC circuit.
Until now.
One Lap of OC (OLOC) is a 100% city loop that's 105.5 miles in length. There are dozens of siganls (I'll count someday), and most of the roads are of the main arterial variety. Speed limits range from 25 to 45 mph, though a 3-mile section of Pacific Coast Highway between the signals at Seal Beach and Huntington Beach is posted at 60 mph. There are exactly zero freeway miles.
We adhere to all speed limits except the one on that 3-mile stretch of PCH, where we go 55 mph instead of the posted 60 mph. Throughout we accelerate modestly at a pace that falls somewhere between old lady and late-for-work commuter, and we look ahead and anticipate instead of tailgate.
In other words, we're not hypermiling, but we are driving in a way that would please our parents or any for-hire passengers with weak stomachs we might be carrying. Hybrids tend to do quite well on this loop, though by nature it is too long for the likes of the all-electric Nissan Leaf (although in the interest of science we should try).
|
2011 Chevrolet Volt |
EPA Rating |
Edmunds LT Test |
Difference |
|
Electric Range (miles) |
35 |
37.6 |
7% better |
|
Electric Use (kWh/100) |
36 |
34.1 |
5% better |
|
Gasoline Use (mpg) |
37 |
34.2 |
8% worse |
The above chart shows how our 2011 Chevrolet Volt has fared so far in relation to its EPA ratings after 12,000 miles of randomized driving.
At first glance, the EPA's electricity ratings come across as too harsh. We understand the cautious approach for full EVs like the Nissan Leaf -- you don't want to over-promise if a roadside stranding (or a bad purchase decision) is a possible outcome.
But this is a plug-in hybrid, so running it out of juice has no ill consequences. In fact, it's expected, a regular occurence. The EPA can afford to loosen up and be more realistic when it comes to the EV mode ratings of plug-in hybrids, I think.
Meanwhile, the Volt's gasoline rating seems too optimistic, even here when the same driving style continues through the transition from battery power to engine-generated electricity. Perhaps we're seeing the effects of decades of learning how to best calibrate a gasoline engine and transmission to do well on a standardized set of dyno-based gasoline test patterns. Perhaps some that EV-mode pessimism needs to be applied to gasoline hybrid operation modes.
Now let's look at how the OLOC city route compares to EPA ratings.
|
2011 Chevrolet Volt |
EPA Rating |
OLOC Observed |
Difference |
|
Electric Range (miles) |
35 |
44.1 |
26% better |
|
Electric Use (kWh/100) |
36 |
28.2 |
22% better |
|
Gasoline Use (mpg) |
37 |
37.6 |
1% better |
Since the regenerative braking function recovers most (but not all) of what is lost at the signals and stop signs, and the start-stop function kills the engine at rest (when it's being used, that is), overall performance can reap the benefit of the loop's low average speed. The 105.5 mile loop takes about 4 hours to complete, which means we're averaging just over 25 mph including all the zero mph rest time at signals.
As such, all three performance metrics improve, especially electricity consumption and e-range.
Our modestly driven Chevrolet Volt did significantly better than the EPA's EV-mode predictions when driven in the medium-density suburban city environmnet of Orange County. It fared better than it usually does in the denser traffic of the West Side, better than it does on wide open freeways. A driving pattern like our OLOC course is quite kind to the 2011 Chevrolet Volt.
Dan Edmunds, Director of Vehicle Testing
mrrizzo says:
03:22 AM, 12/14/11
The Volt has several modes that it can be driven in. I've had my Volt since March and now drive exclusively in SPORT with the gear selector in LOW which aids regenerative charge back. One Saturday while running errands, I traveled 51.7 miles in EV mode staying off the highway.
Does Edmunds ever use LOW gear?
Also, I usually exceed 37mpg while the generator is running. I set the cruise to 67 as much as possible. I've taken two trips to Cape Code (4 hours one way) and averaged 42mpg and one 12 hour trip to the Outer Banks of NC averaged 45 mpg.
To me, the monthly fuel economy charts Edmunds produces does not show how little gas you can use, only what the fuel economy is when you do use it. In 8500 miles of driving, I've used about 44 gallons of gas, 22 or so in that one trip to the Outer Banks. My daily commute is about 20 miles round trip. I'd be curious to know how many gallons of gas Edmunds has used in the 12000 miles.
htr_hardtech says:
05:14 AM, 12/14/11
55 mph in a 60 sounds like your trying to get the most mpg to me. Do posted speed limits or drive with the flow of traffic if the speed limit isnt enough or is too much.
Good example, this morning (5am) I did around 75 in a 65. Why you may ask. I was in the slow lane and didn't feel like getting rear ended. Fast lane was about 85-90.
bodyblue says:
09:12 AM, 12/14/11
The more I read about the Volt the more I like it. I was not impressed at first but it seems to be a good and innovative product. I hope the hype over the batteries dont kill it.
stovt001 says:
09:58 AM, 12/14/11
If there is the perfect market for the Volt, Orange County is it: Left coast environmentalism (and image consciousness, which are mostly the exact same thing), fairly high incomes, suburban housing with garages wired for electricity, good weather, and commutes long enough to rule out most pure EVs.
langjie says:
10:46 AM, 12/14/11
definitely should try this in a leaf....where can you get another one?
stovt001 says:
11:17 AM, 12/14/11
A Leaf relay. I like it.
mfennell says:
01:24 PM, 12/14/11
I thought the EPA number was ridiculous for some time (it's supposed to be a composite figure but I've reached 35 miles at a steady 70mph with the AC on!) but it manages expectations. When it's cold and you're blasting the heat, it crushes your range. You have to pay the full freight of heating the cabin (vs waste heat in an ICE) PLUS the battery performance suffers some.
Today started at 34F, going up to 48 or so, and sunny. I'm going to hit 40 miles where I would easily get close to 50 in the summer. If it stays cold all day and the sun doesn't come out, I expect to bottom out at 30 or so. Put my wife, who only knows one heat position - HI, in the car and I'm thinking low 20s.
rcb268 says:
01:49 PM, 12/15/11
@mfennell: Hahaha! Excellent!
troverv says:
09:54 AM, 01/ 3/12
@mrrizzo Theres no real "low" gear in the volt since it doesn't really have a transmission. The SPort mode simply re-calibrates the accelerator and is more aggressive about providing power.