What increases fuel efficiency in Hybrid Cars ( up by 39% so far)?

Question

The hybrid cars consume less gas (petrol). At the begining ( four years ago) it was expected that the fuel (any fuel) will be saved upto 61%. Some did not believe. Hybrid cars are saving upto 39% till now and research is going on.

Answer 1

Hi,

Right up front, I maintain 51.7 in a Prius as a year long average and live in the upper MidWest where we had frost on the ground last night (still in the 30's).

And I know my 44-46 mpg average on long highway trips more than beats the 30's from Camrys, Accords, Malibus, or any other standard, non-hybrid vehicle in the Prius' size and weight class (mid-size vehicle, 2985 pounds with full gas tanks).

There are several basic ways to increase mileage in a Prius, here are the basics:

1. Buy a digital tire gauge (about $15-20) and use that to check the pressure at least once a week. Throw away the cheapy stick gauges, they're just not accurate enough.

A good, rough rule is 1-2 psi lost on all four tires equals 1 mpg. I have met multiple Prius owners who never check their psi and couldn't get out of the high 30's-low 40's.

2. There are two general schools of thought for acceleration in any vehicle, but especially a full hybrid like the Prius.

Accelerate like you have an egg under the accelerator and you're trying to roll the egg out, not make omelets.

Press the accelerator hard to get up to speed quickly and then ease off and hold your speed constant.

I personally have tried both for a year and get about 3-4 mpg more with the gentle acceleration (egg).

3. Double the distance you usually stop in. If you normally start to press the brake at 100 feet (let's use easy numbers for this), then take your foot off the accelerator at 200 feet and coast until the 100 foot mark. Then press the brake pedal down gently to the stop.

The Prius recharges it's nickel metal hydride (NiMH) in three ways, one of those is by the friction of the wheels rolling on the ground (the other two are the gas engine running and pressing the brake pedal).

Use the screen which shows the large yellow bar on the right and the 1/2 hour graph in 5 min blocks to gauge your economy. Don't use the video game screen that shows the power flow around the car, it's too distracting.

Doubling your stopping distance, you'll watch your mileage bar jump from the 50-75 braking range into the 75-99 range every time you do it.

4. Try to avoid ethanol blend gasolines. Ethanol is grain alcohol and is not as energy dense as gasoline so you get less bang for the buck.

Your mileage will go down about 10% for each 10-15% ethanol blend. On a vehicle that gets 45-50 mpg, that means 4.5-5.0 less mpg, just for the fuel.

Plus, corn-based ethanol is a government boondoggle that needs to be changed. It takes about 1.26-1.29 gallons of pure fuel to create and distribute 1 gallon of ethanol, and that's according to our own federal government websites.

5. Tires on a hybrid are important. For example, the original tires on a hybrid are "low-rolling resistance" or LRR's tires.

If different tires have been put on that are not specified as LRR's, your mileage will go down by 3-5 mpg or possibly more and there would be nothing you could do, short of changing the tires.

LRR's have a strengthened sidewall that holds the tire more vertically than a standard tire and allows it to roll on the ground with less energy.

6. How much additional weight are you carrying around or do you have an aftermarket accessory installed, such as a roof mount cargo or bike rack or rear hitch bike rack?

The additional air drag from a rack will lower your mileage easily 4-5 mpg, especially if the roof rack is empty, believe it or not.

7. Remember that your mileage will go down when temps get to freezing or below, no matter what.

Your gas engine will run more (pretty continuously) to produce heat for the cabin, your tires will require more energy to move through slush and road salt/de-icer, and traffic is always worse when conditions deteriorate.

This is not as big a factor now that spring may finally be coming, but it is good to keep in mind for year-round driving.

Every little thing adds up. If you have E15 in the tank, your tire pressure is down by 2-3 psi, and you are driving more aggresively than needed, you could easily be losing a potentional 8-10 mpg.

And one last thing, don't fall for gimmicks like nitrogen in the tires, so-called "super alignments", supposedly high mpg fuel additives or extremely low viscosity oils.

As an example, extremely low viscosity oils will actually slip past the piston seals (and other components) and get burned up in the cylinder, causing you to burn more oil than usual ( a very small amount is normal) and affect the performance of the gas engine.

Stick with good oil, not the cheap stuff, just avoid extremely expensive "race" oils.

BTW, vehicles like Geo Metros did not have anywhere near the comfort, safety, and convenience features that the US government regulates and modern consumers demand in current new vehicles.

Just adding the additional door beams, A/C system, airbag passenger weight and deceleration sensors in the seats and frame (airbags only work because you stop suddenly, not just because you hit something), ABS sensors and brake fluid pressure modulators, tire pressure sensors, and all the other systems that are either required or people demand on a vehicle add hundreds of pounds of weight, which lowers mileage dramatically. There's no way around that.

Plus, almost every person buying a modern vehicle would never consider one without A/C, airbags, four doors, and other essential basics like traction and stability control systems, which doesn't even include stereos, navi systems, and other add-ons. Even small, highly efficient vehicles like the Yaris or Fit advertise the options and safety features as much as the gas mileage.

And the huge premium for purchasing a hybrid myth has been debunked here many times. Take a look at my other posts here in Answers for full numerical details. This myth usually compares a $21,000 Prius to a $14,000 Yaris or $16,000 Corolla, when that would be like comparing a Corolla to a Camry. The cheaper vehicles are not in the same catagory and do not have the same comfort, room, performance, features and options as the Prius or Camry Hybrid. The same is true for Honda with the base Civic to the Civic Hybrid to the Accord.

Take a look and if that doesn't do it, let me know.

Answer 2

In stop and go traffic, the gas engine shuts down when not needed to save gas.

On the highway, the cars get similar efficiency to other cars of the same size/weight class.

Answer 3

while there is a gain in efficiency in hybrid cars, it isnt as big as you might think. the epa driving cycle test is geared to give a hybrid vehicle an advantage compared to a gas only powered vehicle. how does it do this? simple, at low speeds the test driver, not a government employee but one from the automaker, can drive the car in such a manner as to run on the electric motor only, and even when accelerating to freeway speeds the test driver can maximize the use of electric only operation to avoid using gasoline. thus the test is weighted in favor of hybrid cars. when the average person drives a hybrid, they find that they dont get the stated improvement in mileage that the epa allows the automakers to brag about.

one more thing to consider is that the average hybrid costs about $6000 more than the equivalent gas engine only model, and it takes several years before that difference in price is recovered.

Answer 4

It is most practical to think of a hybrid car as a gasoline-powered vehicle with an exquisitely-controlled engine.  Careful driving with a conventional light gasoline-powered car or a small diesel can usually match their performance: the old Geo Metro can beat most hybrids.