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Corn-Fed Impala

Written by PFM Staff

Does an E85-powered sedan get the same fuel economy as a gasoline-powered one? Or does it get 5% less? Or 15% less? Or 30% less? How is the performance when using E85? Can you really use ethanol in one fill-up and gasoline in the next?

To answer these questions and more, we borrowed a 2006 Chevrolet Impala powered by the 3.5L V-6 from GM Fleet, and put 1,000 miles on it. All these 3.5L V-6 engines are E85-compatible. This is regular production, not a special order.

Heads up. This is not the 9C1 police package version of the Impala. Nor is it the 9C3 “street appearance” version of the police package cars. It is a non-police, pure retail (or fleet) version. The police version is not available with the E85-compatible 3.5L engine. And the 3.9L police engine cannot currently use E85 fuel.

The retail 2006 Impala is available in a variety of trim levels, including the LS, three versions of the LT, the LTZ and the V-8 powered SS. We drove the 1LT version. Side-curtain (roof-rail) airbags are standard equipment on these retail Impalas. However, ABS is an option.

Overall, the 2006 Impala has ample head, shoulder, elbow, hip, knee and legroom for most officers. New for 2006, the recessed dash makes much more room for the passenger. The car just feels roomy.

The Impala has excellent seats. The seat back bolsters and seat cushion bolsters both offer good lateral support. Yet the seats are very easy to get in and out of. The seat cushion is nice and wide but could be a little longer for thigh support. The seat cushion center insert is relatively soft, and the seat back center insert is relatively hard...all together an excellent combination.

Driving Impressions

What are the big advantages of the 3.5L Impala? First, it is one of the few admin-class sedans available right now that is E85-compatible. The police Impala with the 3.9L V-6 is not. The Charger and Magnum are not. While the non-police Crown Victoria is, the Five Hundred is not.

Second, when running on unleaded gasoline or gasohol (E10), the 3.5L Impala gets much better fuel economy than all these other admin-oriented sedans. That is 30 mpg ACTUAL on the highway, not an inflated EPA estimate.

Ultimately, regardless of how the retail Impala may feel on the first driving impression, the 3.5L Impala is not pursuit-capable. It has retail-oriented touring tires and retail-oriented brake pads. Do not expect the non-police, non-pursuit capable Impala to perform during emergency driving like the 9C1 police Impala.

If for some reason, these retail 3.5L Impalas are pressed into more aggressive patrol use, at the very least, upgrade to two police components. Install semi-metallic brake pads and the same 16-inch high performance Pirelli P6 Four Seasons tires that come as original equipment on the police version.

E85 Ethanol

E85 is a mixture of 85% ethanol and 15% gasoline. Gasoline is STILL an important part of E85. Pure ethanol has a low volatility point, making it more difficult to vaporize during very cold starts. Gasoline is added to the ethanol to help cold starting and warm up performance.

What is different on an E85 vehicle? One major system and a bunch of minor parts. The major addition is the fuel sensor that detects the ethanol-to-gasoline ratio. All three manufacturers use different sensors and different sensor strategies. However, the end result is the same, the exact ratio of ethanol-to-gasoline regardless of what you put in the tank.

You can put straight gasoline or gasohol (E10) or ethanol (E85) in the tank of the E85-compatible car, and the sensor will figure it out. To the point, you can fill with pure gasoline, then add 10 gallons of ethanol (E85), then 10 gallons of gasohol (E10), then 10 gallons of ethanol (E85) and then 10 gallons of pure gasoline.

The fuel sensor will detect the exact alcohol ratio at any one point in time and make the precise PCM changes, even though the exact ethanol-to-gasoline ratio changes at every fill. The transition period, as the sensor detects shift in ratio, will take a few minutes of driving. The vehicle will not be at peak performance during this period. However, this transition period is very subtle.

We started off with the 3.5L Impala full of pure gasoline and ran some performance and mileage baseline tests. At ¼-tank, we filled with E85 and followed that up with E85 for the rest of the review with one exception. Low on fuel, and unable to find any E85 (a pretty common challenge), we put in 10 gallons of gasohol (E10). We used E85 the rest of the time. The transition from gasoline to E85 to E10 and back to E85 went totally unnoticed, even though we were paying close attention for drivability issues.

Some minor parts in an E85-compatible vehicle are modified to handle E85 fuel. Alcohols are corrosive. The fuel tank, fuel lines, fuel injectors, computer sensors, and other support parts are upgraded. Any part that comes in contact with the alcohol-based fuel is changed to a material tolerant of alcohol. Typically, this means stainless steel metal parts and Teflon®-lined plastic or rubber parts.

Engine Oil

Does the E85 engine require a different kind of engine oil? Maybe! The concern is that unburned ethanol, especially during rich, cold starts may migrate past the piston rings. This may result in cylinder wall washing, i.e., remove the cylinder wall lubricant and cause ring or wall wear. The unburned ethanol could also run down into the crankcase and dilute the engine oil.

At least, these were the concerns when Ford originally specified the use of synthetic oil in its Taurus FFV. Ford no longer requires such a special oil. The GM vehicles do not. However, some DaimlerChrysler E85-compatibles may still require a synthetic oil. Do the smart thing...check the owner’s manual for the exact vehicle and powertrain in question.

Other than initial cost, synthetic engine oils have no downsides and may be an overall better lubricant. However, the formal word from GM, Ford and DaimlerChrysler is that the oil change interval for petroleum-based and synthetic engine oils is the same. The Big 3 will not permit an extension in change intervals just because synthetic oil is used.

Cost of Repairs With E85

Repairs? Are E85-compatible vehicles more expensive to service and maintain than the same vehicle powered by gasoline? No. In fact, because ethanol runs cleaner than gasoline, the engine and exhaust system maintenance expense may actually be less. A number of studies are under way to confirm this. Of course, the use of synthetic engine oil, with the same change interval as petroleum-based oil will slightly increase operating costs.

What about a fire fueled by ethanol? Obviously, this is an extremely important and sensitive topic in law enforcement. The National Fire Protection Association (NFPA) Code 30 and 30A establish firefighting techniques and chemicals for fighting fires fueled by unleaded gasoline. Per the NFPA, these same techniques and chemicals are appropriate for fighting ethanol-based fires.

The Ford Crown Victoria Police Interceptor will soon be E85-compatible. Per Ford Fleet, the (optional) onboard fire suppression system on the CVPI is as effective on ethanol as it is on gasoline.

E85 Fueling Stations

Even in corn-fed Indiana, it is difficult to find E85 fuel, at least at the retail level. This is not an issue with onsite bulk storage fuel tanks where E85 can be delivered. However, this is definitely an issue for departments whose fuel comes from retail stations.

The Internet is not much help. A number of Web sites list E85 fuel locations by state. However, many of these are inaccurate. New locations are not added on a timely basis. Some locations listed as having E85 do not even have an E85 pump. Other locations that at least have an E85 pump run out of fuel and are slow to refill, pending customer demand.

As of September, only 800 out of 170,000 filling stations in the U.S. sold E85. According to the most recent data from the National Ethanol Vehicle Coalition, of these 800 stations, more than 200 are in Minnesota, leaving less than 600 for the rest of the country. Few stations exist on the coasts. This is definitely a Midwest thing.

Alky Dragster

Vehicles powered by E85 typically produce better performance than the same car powered by gasoline. With an octane rating of 100 to 105, the engine’s powertrain control module (PCM) can allow more aggressive cam timing, and spark advance before it detects ping (pre-detonation).

The performance of the police package Impala is well-documented. The 200 hp 2005 and older Impala with the 3.8L V-6 hits 60 mph in 8.8 seconds and 100 mph in 25.3 seconds. The 240 hp 2006 Impala with the 3.9L V-6 reaches 60 mph in 8.8 seconds and 100 mph in 23.6 seconds.

Running on E85, the 211 hp 3.5L V-6 Impala hits 60 mph in 9.1 seconds but reaches 100 mph in a comparatively sizzling 22.9 seconds. At lower speeds, the 3.5L Impala is about as responsive as the old 3.8L V-6 version. At higher speeds, the 3.5L Impala feels like the new 3.9L V-6 version. The passing performance from the 3.5L engine is better than the older 3.8L.

Bottom-line Operating Costs

Because ethanol (alcohol) has less energy value than gasoline, vehicles running on E85 do, indeed, suffer lower fuel mileage. E85 proponents report 5% to 10% less fuel mileage. That is not even close. Even the EPA, well-known for unrealistically high fuel mileage estimates, has the E85 vehicles at 25 to 30% less efficient than the same car on gasoline.

Under similar highway driving conditions, we got 29.6 mpg in the 3.5L Impala on gasoline and 19.3 mpg on E85. That is 35% less mileage on E85. In a mix of urban patrol and light traffic enforcement use, the Impala on E85 averaged 18.2 mpg. In similar city driving, the same Impala on unleaded gasoline got 24.5 mpg. That is 26% less mileage on E85.

It is pretty easy to calculate the fuel economy difference between straight gasoline and ethanol. But fuel consumption is just half of the total cost calculation. The other half, the cost of fuel, is much harder to estimate. E85 is as taxed, subsidized and politicized as gasoline…and in the near-term, probably more so. Local incentives of $0.40 per gallon for E85 are common. Rapidly changing market forces mixed with politics make the price of E85 impossible to predict state by state, or region by region, or at any point in time.

In mid-summer 2006, we drove the Alky Impala in three Midwestern states. In Chicago, E85 was $0.30 a gallon cheaper than regular unleaded gasoline. In Louisville, E85 was the same cost as regular unleaded. In Indianapolis, E85 was the same price as premium gasoline.

Do the math. During our review, gasoline was right at $3.00 and we got almost 30 mpg. Getting almost 20 mpg on E85, this alternative fuel would have to cost $2.00 to result in the same total fuel cost. That is just not happening.

Facts are stubborn things…total fuel costs will go UP with E85...under the current engine technology and fuel-pricing strategies. The use of E85 is definitely patriotic, certainly in the best long-term interests of the country, and produces fewer greenhouse emissions, but it is also more expensive to use than gasoline.

Future of E85

The real uncertainty for E85 is the source of future feedstocks for E85. The American Petroleum Institute, which obviously has a stake in the gasoline versus ethanol issue, indicates that ethanol would not be a viable substitute for gasoline until refiners find ways to make it from material other than corn.

Today, the best way to think about E85 is as an alternate fuel, not a lower-cost fuel. As it stands now, E85-capable vehicles give the police department an option to use either gasoline or ethanol, depending on which is the lower total cost and which fuel is available. And that alone is a valuable option for emergency services.


Published in Police Fleet Manager, Sep/Oct 2006

Rating : 3.6


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