This is usually the first question people ask me. Others include: Do you plug it in? Is it slow? Does it short out when you drive through puddles?
The answer to the first question isn’t so simple.
First, you have the Environmental Protection Agency estimate. Basically, the EPA method of creating a standard for fuel economy hasn’t changed since 1985. In 1985, most of us thought electronically controlled multi-port fuel injection was the wave of the future; an efficient car was a Chevy Chevette, or my dream car, a 1981 Volkswagen Rabbit diesel pickup. 
The EPA standard for fuel consumption rate is out of date and it’s about to change in 2008 for all cars.
The current standard leans in favor of hybrids because of the out-of-date testing methods. We are all in for EPA sticker shock in the fall of 2007 when the new testing methods kick in. Under the new testing method, fuel economy estimates will drop for all vehicles. Conventional (non-hybrid) vehicles would drop on average by about 10–20%. For hybrid vehicles, the city mpg estimates would drop 20–30% from today’s stickers. For highway mpg estimates, the change is about the same as for conventional vehicles. Check out the EPA site directly for more information. http://www.epa.gov/fueleconomy/420f06009.htm
Here is one proposal of what a new sticker might look like.
All hybrid car manufacturers know that real world driving doesn’t match the stickers, but who can blame them? It’s a competitive market and the EPA creates the standard. Yes, the sticker on my 2005 Honda Civic Hybrid says it gets 51 MPG highway, and it’s hard to get that, but a Hummer H1 with a gas V-8 gets under 10 and I don’t hear people arguing about that EPA sticker.
With all vehicles, a lead foot means bad mileage. My experience is that a lead foot with a hybrid can really widen the gap between high and low.
Think of what’s under the hood. In a conventional car, you have a fuel injected engine. This system takes into account many conditions from sensors and interprets them though a computer to maintain optimal operating conditions. In a hybrid, you have a fuel injection system and then the fun begins.
On my Civic, the engine can shut down individual cylinders and shut off entirely when not needed. A battery that sometimes charges, sometimes supplies power and sometimes sits idle. The battery trickle charges during cruising if it’s below a certain capacity, won’t charge if it’s above ¾ full, unless you are braking, and charges at idle if it’s almost empty. Since my car has a manual transmission, the battery won’t charge during braking if I prematurely push in the clutch. The more you maintain the battery level, the less the gas engine needs to charge the battery and the better the fuel economy.
Add to the battery and engine dynamic: The engine doesn’t shut off when it gets below freezing. When you are using accessories like A/C, it takes energy from the battery and/or engine. It’s the dead of winter and you are making a lot of small trips. A lot of factors affect mileage in a hybrid.
On a leisurely trip to the mountains of North Carolina with some highway and back country roads, my average was 53 mpg for 1,000 miles. On a trip to Gettysburg out Route 234 going mostly 50 mph, I get over 50 mpg. On a stressful, frigid day when I am buzzing around York County making 20 stops shooting pictures, it could drop as low as an average of 39 mpg.
Anyone have some real-world mileage numbers they would like to share? I would love to hear your comments. Any tips?
A team of drivers got 109 mpg out of a Toyota Prius by using a “Pulse and Glide� technique. Check it out. http://hybridcars.about.com/od/ownership/a/pulseandglide.htm
Some up-and-coming domestic hybrids with some promising mileage figures:
2006: Saturn Vue SUV, with 27/32 mpg. source saturn.com
2007: Chevy Tahoe, GMC Yukon, up to 35 percent mpg boost. Chevrolet Malibu, 15 percent increase.
GMC Sierra and Chevrolet Silverado pickups increase fuel economy 10-12 percent.
2008: Chevy Silverado and GMC Sierra pickups that get up to 35 percent mpg increase.
Diesel-electric Dodge Ram pickup with 15 percent mileage boost. source MSNBC
Ford is already in the game with the Escape Hybrid (which uses technology licensed from Toyota) at 33/29 mpg for 4WD. source ford.com
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--My '04 Prius has been sipping fuel at an average rate of about 53 MPG over 20,000 miles. I'm probably one of the few people who wishes he lived further from work --if it weren't for the short MPG robbing commute, I'm confident my average would be pushing 60 MPG...oh well.
--Personally, I like to accelerate briskly up to speed and then let up on the juice just enough to kick the engine off (the "pulse and glide" technique). This technique works for full-hybrid cars like the Prius that can run on electricity alone, but may not apply to other hybrids that require the engine to run when the wheels are turning.
--One tip to save fuel that works for all cars is to avoid long "warm-ups" while in park. Instead of burning fuel sitting in the driveway (0 MPG), might as well put it in gear and use that same fuel to get you down the street (non-zero MPG). The engine will actually warm up faster by gently driving it for a few minutes. Contrary to popular belief, it's also better for your engine. Better fuel economy, faster warm-ups, and less damaging to the engine...What's not to like?!
My 2001 Hyundai Elantra gets about 34mpg on average. I've trained myself to drive for better mileage (something of a zen artform, really) so it's probably better mileage than most drivers get on the car. I calculate my average mileage with every fill-up at the gas station, and I have a meter in my car that gives me a live reading of my mileage while I drive.
One little trick I found for saving on gas in downtown Harrisburg -- drive the speed limit. It can be really hard to keep your speed at 25mph, but by driving exactly 25 down 2nd Street, you can go the entire length of the road without getting a single red light. Maintaining the same speed/rpm gets me the same kind of mileage I get driving on the highway... it's win-win.
I bet the traffic lights are timed. I think Philadelphia Street in York was timed a few years ago to give people a viable alternative to Rt. 30. Someone should come up with a "green route" map that gives the stretches where lights are timed.