 2010 Lexus HS 250h. Click image to enlarge |
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2010 Lexus HS 250
Winnipeg, Manitoba – The newest hybrid sedan from Lexus has now completed its two-month stint with us, so it’s time to take a final look at how well it fared.
I went into this long-term test with the intent of finding out how the HS 250h – an entry-luxury car that’s available only as a hybrid – would handle a cold Prairie winter. I noted in my last report that I was hoping for a cold snap in February. While it turned out to be a somewhat mild month overall, the mercury did dip down into the minus-20s enough over the season to give me a good idea of how the car would perform through a more normal winter.
Our last update went over the specifics of this hybrid’s fuel consumption. With official ratings of 5.3 L/100 km in the city and 5.9 on the highway, my observed city consumption has ranged from 7.5 L/100 km in milder winter conditions (between zero and -10) to 9.5 L/100 km in a more normal -20 C environment. I also had single-trip extremes ranging from a low of 4.9 L/100 km to a high of 11.7.
 2010 Lexus HS 250h. Click image to enlarge |
My “urban highway” experience landed me in the low-6s for consumption on roads with a cruising speed of 80 to 90 km/h. I have since taken a highway trip involving a cruising speed of 110 km/h and a trip distance of 100 km at -9 C, and found that my average consumption was up at 7.2 L/100 km, which is more representative of what owners might experience on a winter highway trip of their own.
So why the discrepancies? Compared with the official ratings, my observed fuel consumption ranged from 40 to 80 per cent higher in the city and 20 per cent higher on the highway. Before we get into hybrid-specific factors, it’s important to understand that there are several reasons you might encounter higher consumption than the ratings indicate, no matter what you drive. As we’ve stated before, factors like driving style, traffic conditions, and weather each play a huge role in determining how much fuel will be required to get you between points A and B.
Going into this test I hypothesized that gas-electric hybrids have an advantage over conventional fuel-powered cars in the laboratory tests that are used to develop the official ratings. This was an assertion I made not based on knowing how the tests were conducted but rather on my own anecdotal evidence. I contacted Natural Resources Canada, the government body that, in conjunction with Transport Canada, approves the fuel consumption test procedures and collects the results from vehicle manufacturers. Their efforts culminate in the publication of the annual Fuel Consumption Guide containing the EnerGuide numbers that also show up on the window stickers in new car lots across the country. More information can be found at Natural Resources Canada’s website.
 2010 Lexus HS 250h. Click image to enlarge |
After a few e-mails back and forth, it’s now clear exactly why I’ve seen this trend in the hybrids I drive. While our test procedures have been based on those used by the U.S. Environmental Protection Agency for more than 30 years, the EPA adopted new procedures in 2008 that account for higher highway speeds as well as extremes in weather. Let’s hope the Canadian government follows suit. But for now, we make do with laboratory tests of vehicles that are stored at 23 degrees C prior to the test. So even though the test begins with a “cold” start as far as the car’s fluid temperatures are concerned, the ambient air temperature is much closer to that of a warm summer’s night. Check out FuelEconomy.gov for specifics on the test procedures.
It all comes down to the fact that hybrids have very little, if any, fuel consumption advantage over gas-powered vehicles during the warm-up period. So every time the car is started after sitting in sub-zero conditions, the system won’t begin the engine shut-off function (one of the primary features of hybrid vehicles that help them save fuel) until normal operating temperatures are reached. In my winter experience, that length of time was as little as four minutes at -5 C, but at -20 C the engine didn’t shut off even once during a commute that lasted more than half an hour.
So at the end of the day, it’s important to know what to expect from a hybrid during a Canadian winter. In the case of the HS 250h, one can anticipate a fundamental luxury that Canadians look for: quick start-up, quick interior warm-up, and toasty seat warmers in a short time. But one also needs to be aware that fuel consumption in cold weather can deviate significantly from the published ratings; much more so than with vehicles that have conventional gasoline-only powertrains.
