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EUROPRIUS

Prius

Better Gas Mileage 


Overview

    Toyota's sophisticated hybrid system allows nearly all drivers to achieve better than 40 mpg in the summer.  In the winter, the high 30's are more typical.  Proper use of an EV Switch during the winter should keep you in the mid 40's during the winter and even higher in the summer.  Everyone drives differently and this can materially effect the mileage you get.  Following is a list of techniques that have been used to truly get the most out of your Prius.  How many of them you use is up to you.

Break-in Period

     Give any hybrid a full six months and/or 10,000 miles to get broken in. The biggest impact occurs in the first 2,000 miles or so, and it may take as much as 15,000 to achieve peak mpg's. Hybrid owners commonly experience a 10-15% improvement in fuel economy after the new car smell has drifted away.

Use of an EV Switch

      Start your Prius.  When the Toyota emblem comes on, hold in your cruise control lever for 2 seconds (I actually use a count of 4).  That should work.  If you get three beeps you don't have enough battery power (at least 4 bars) or your onboard computer is multi-tasking.  If you miss the Toyota emblem, you can wait for your car to stop running (the engine goes through a startup cycle if EV is not initiated).  Drive as you normally would. Accelerating, driving over 33 mph, and braking will all charge your battery.  When you find yourself in any situation where you will being going less than 34mph, then just switch back to EV mode.  This is a great way to get the most MPG out of your Prius.  Occasionally, it will be too hot outside or two cold outside or your onboard computer will be multi-tasking, and your Prius will not be able to change into EV Mode.  You will see the message on the screen, "Cannot change into EV mode now".  This is normal.  Annoying sometimes, but the car is great, not perfect.

Route Selection

     Speed is your enemy. The ideal routes have long stretches without stops, and speed limits of 30 – 35 mph. (The sweet spot for most hybrids, in "steady state" testing, is between 40 and 45 mph.)  Don't be concerned about hills, especially routes with short steep uphills and long gradual downhills. The glide or coast on the way down—especially if it's uninterrupted—will more than make up for the extra energy to get to the top. And the downhill stretches will give you a chance to recharge your battery through regenerative braking.  Pick routes that are less windy. A hybrid's aerodynamics are streamlined for head-on gusts, but swirling and sideways winds can destroy high mpg. Tail winds are great.  Experiment with multiple routes to see which paths consistently produce the best mileage.

When to Drive

     Cold starts are mpg killers. The Prius and other hybrids get the worst mileage in the first five to ten minutes of driving, unless you are using an EV Switch  Try to get all your errands done in one outing. If you can help it, drive after the day has warmed up. Hot humid air is the least dense, and produces the least air resistance.  Avoid rush-hour traffic, if at all possible, unless of course you have an EV Switch.  Rush hour traffic is great with an EV Switch.  Do your best to skip driving during rainy, slushy or snowy conditions.

Tire Pressure

      Tire pressure (i.e., rolling resistance) has a significant influence on fuel economy, and an obvious impact on safety and the quality of your ride. Do the research, and make your own decisions about how far to take the tire pressure to maximize mileage.   Drivers getting the highest mileage recommend using the recommended maximum tire pressure on the sidewalls—not the psi supplied by the automaker on the doorframe.   Maintain the maximum recommended tire pressure. Check the tire pressure regularly so the pressure does not fall below the maximum level.

Fuels

     Low octane gasoline is best. (There is actually less energy in high-octane fuel.) Some convenience stores may use more additives than "name brand" gas stations.  Watch out for ethanol.  It can rob you of 10% of your MPG.  In the winter it is required to be added to gasoline by law, but starting in the Spring, you can buy gasoline without it.

Distance from Other Vehicles

     Be aware of road conditions. The most important factor in maximizing your mpg is your ability to take your foot off the accelerator absolutely as soon as know that you'll need to slow down or stop—and getting into "glide" mode.  To give yourself time to stop and coast, create space between you and the car in front of you—except when you have the opportunity to "draft" behind larger vehicles on the highway. You can obtain the benefits of drafting while maintaining a safe distance of 150 feet of more.

Starting & Warming Up

      Frequent short city trips will not produce good mileage, even though the Prius is rated very high for city driving. Combine errands to reduce the number of warm-ups.

Dashboard Displays

     There are two schools of thought about using the Prius's display to maximum effect.

     Simple: instantaneous mileage numbers. Learn what produces the best results by watching the effects of your experimentations. Don't worry about the arrows that appear on the "Energy" display.

     Advanced: Use the Energy display to watch the direction of the arrows. Drivers getting the best mileage are able to use split-hair changes in how they press on the accelerator and brakes to move energy from the gasoline engine to the wheels and/or the batteries—or to get all arrows to disappear completely from the screen, in what is referred to as "glide mode." (More on this below.) Learning how to get the system into these different states is only possible if you monitor the Energy display and keeping an eye on the results of your fancy footwork.

Accelerating & Cruising

     Never mash your foot to the floor. Accelerate slowly especially from a standstill. (Some Prius drivers prefer moderate acceleration before gliding with the engine off.)  If you would like to simultaneously send energy to the wheels and to the hybrid batteries—for example, when you have the headlights on at night and you have a low charge, follow these steps:

    While traveling above 20 mph, slightly lift your foot off the accelerator (but not all the way).

    Reapply your foot gently, until the Energy display shows the energy flow going to the wheels and the batteries. If you push the accelerator too soft, all arrows will disappear (and you will be gliding). If apply too much pressure to the accelerator, all of the gasoline will go to the wheels.

    When you need to enter a highway or otherwise rapidly accelerate, simply stomp on the gas and go. The battery power will "assist" the gasoline engine, thereby reducing your fuel use as much as possible.  For highway driving, get best results by setting cruise control at 55 mph. For every mph over 50 mph, you lose approximately 1 mpg. Slowing down from 65 to 60 mph or from 75 to 70 mph will save you approximately 5 mpg.

Braking & Deceleration

     In the eyes of advanced Prius drivers, the way you slow down and brake is much more important than acceleration techniques—and the goal is to "glide" (description below) at every opportunity, regardless of the traffic conditions.  The main idea is to control the amount of braking that is used to regenerate energy to the batteries. (Regenerative braking is essential for keeping energy in the batteries, but a little bit goes a long way. Avoiding overuse of regenerative braking will prevent you from slowing down more quickly than necessary. Extending your glides and coasts is a key to maximizing mileage.)

     Native Alaskan people have many words for "snow," and Prius hypermilers have at least four words for how to brake. Use the least aggressive method to travel as far as possible before needing to accelerate again:

Gliding (least aggressive) – While traveling, remove foot from accelerator. Then, ever so slightly, re-apply pressure until all arrows disappear from the Energy screen. You'll a feel slight surge forward.  This technique will only work when the car is warmed up. You can glide at any speed, but it's difficult to get the arrows to disappear at speeds higher than 40 mph. At the higher speeds, even if you are gliding, the internal combustion engine will spin in order to protect the smaller electric motor from getting damaged. Above 40 mph, the engine is spinning but no gas is being used. Under 40 mph, the gas engine is not spinning. (Some Prius drivers report a "sweet spot" at 39 mph.) 

     Coasting (slightly more aggressive) – This kind of braking is much easier to explain. Simply remove your foot entirely from the accelerator, but do not apply it to the brake. Regenerative braking is engaged, so you will slow down more quickly than gliding.  

     Regenerative Braking (aggressive) – Press down on the brakes, but not firmly. As you press, you'll obtain more regeneration than with coasting, and the electric motors (now acting as generators) will make you slow down quickly.  Mechanical Braking (most aggressive) – Firmly stomp on the brakes to immediately stop. You will obviously use this style of braking if a vehicle or pedestrian jumps in front of you. To recap, the most important point: Anticipate the need to stop so you can slow down in a glide or in the least aggressive manner. If you do nothing else but get your foot off the accelerator more quickly, you will increase your mpg.  Another "magic number" is 7mph. Below 7 mph, regen stops and friction brakes are engaged—wasting energy that could be stored in the battery. Try to avoid slowing below 7 mph by decelerating earlier while approaching a red light, so that it turns green before you get there.

Idle versus Shutdown

     If you need to remain stationary for no more than ten minutes or so—stopping to run quickly into your house or pick somebody up—place the Prius into park, but don't shut down. Turn off the heating, cooling, lights, and other electric accessories. Push the "Park" button. The goal is to avoid shutting down and restarting, at which time the Prius will run through a startup cycle that uses gas.

Gear Selection

     There are not a lot of gear selections to consider. (Think of your foot as the main control for maximizing mileage.) The one exception is the B gear. The B gear should be used only if you are going down a long hill. The B gear lets the engine slow down the car without overusing your brakes and over-charging the batteries.

AC and Accessories

     It's best to avoid AC and Defrost whenever possible. Using the vent function with the temperature set to your preferred comfort level works well on long trips.  On hot days, set the AC two degrees lower than the outside temperature or to 85, whichever is lower. This setting keeps air coming into the Prius using the least amount of energy.  Avoid using the MAX setting.

Cruise Control

     Cruise control, which provides smooth acceleration and allows the computer to make the fuel-saving decisions for you, is recommended in most situations. It works well on flat driving, and is excellent for non-congested highway driving.  Set at 55. (Good way to discipline yourself to keep your speed down.) Lower speeds will produce even better results.  Cruise control is not nearly as good in hilly terrain, where uphills produce aggressive driving and too much regen braking on downhills. When you're going downhill in cruise control, you can give a little push on the accelerator, which will disengage regen and give you even more speed. Maintain safety by not allowing to much speed to build up.

Advanced Techniques

     The Pulse and Glide technique, which has allowed some drivers to achieve exceptional mileage, is ideal for roads that allow 30 – 40 mph unobstructed driving. Pulse and Glide will be more difficult in any road conditions with busy traffic or numerous traffic signals.
Accelerate moderately (not babying accelerator, but not gunning it) to 40 mph.

Then ease off the accelerator. Then, ever so slightly press down on the accelerator again and hold the pedal in that position.

Glide (engine on but not turning over and transmission in neutral). At this point, the energy screen should not have arrows going in any direction. This state has been referred to as "dead band." If you press too much, repeat the process of easing up and pressing down again until you find the right spot. At this point, you are coasting without any energy being used to charge the battery.

Coast down to 30 mph.

Gently accelerate Gently accelerate (pulse) back to 40 mph.

Repeat steps, alternating between gentle accelerations to 40 mph and gliding down to 30 mph.