Improving Fuel Economy AND Performance together on 2004 Toyota Prius

For the most part engines perform the similarly with burn rates measured in lbs/perHp/per Hr. The standard of efficiency is already reasonably high, but making available, or using more power will inevitably mean the engine consumes more fuel.

There have been supplement battery packs available that enable you to drive short trips on battery only, subsequently improving gas mileage dependent on use. There were claims of 100 mpg and battery performance to 50kms. The downside is the expense and weight of the supplement battery.

Lowering the car will very slightly improve the Cd but at the risk of scraping on undulating surfaces. Aftermarket spoilers, air dams and diffusers are of doubtful worth unless they come with a wind tunnel approved documentation issuing a new specific drag (Cd), which is an unlikely circumstance.

 

The change you seek is in you. Changing your driving style to match your goals will be more effective (and cheaper) than any of the dubious changes you have planned for the car.
http://priuschat.com/forums/gen-iii...18-looking-speed-vs-mpg-graph.html#post912447

The G7 brace on ebay is a cheap placebo. g7 plate prius items - Get great deals on eBay Motors, Prius items on eBay.com!

The scan gauge II can help you understand what the car is doing. http://www.amazon.com/dp/product/B000AAMY86?tag=priuschatcom-20
PriusChat Shop : ScanGauge II Scan Tool + Digital Gauges + Trip Computers [ScanGaugeII] - $159.95

If the tires are the stock Goodyear Integretys, or a non Low Rolling Resistance tire, then even Walmart Goodyear Viva Authority Fuel Max tires will be a step up. 42 pounds in front/40 pounds in back.
Goodyear Viva Authority Fuel Max Tire P185/65R15 Customer Ratings & Reviews - Top & Best Rated Products - Walmart (I was agreeing with everything this guy said until I realized it was me)

 

Totally agree. Many of those dubious changes will have little to no effect on mileage improvement. Don't bother. Save your money.

As for "I'm really excited about the 55-ish mpg", I've had one for >5 years. I've never achieved 55 mpg on an entire tank. My current trips are very short (yielding "poor" mileage). My previous commute was NOT conducive to pulse and glide (only could do it for a short section and only safely in the day on that stretch) and I kept up w/flow of highway traffic in CA and then some.

Out of curiosity, what mileage do you expect to get? 55 mpg?

If you're getting the "55-ish mpg" from the old method EPA ratings, keep in mind, it was adjusted downwards by formula due to EPA method changes for the 08 and beyond model year (no, the car didn't change significantly). Revised EPA ratings are 48 city/45 highway, 46 combined. http://web.archive.org/web/20080618...-advice/most-fuelefficient-cars-206/index.htm is what Consumer Reports got. (Their city test must be pretty harsh.)

As for PHEV kits (which I have no interest in), the two that stand out are the HyMotion kit (http://priuschat.com/forums/gen-ii-...57-review-hymotion-battery-plug-in-prius.html) or the Enginer kit. If you're as hardcore as TheForce and have routes as conducive as he does, you can get numbers like http://priuschat.com/forums/gen-ii-...prius-ii-plug-in-hybrid-electric-vehicle.html. Remember that Prius isn't an EV nor a PHEV. It has quirks like the ICE having to spin once you get >41 mph.

From the little I've poked around on the Enginer kit, it seems rather finicky and unreliable.

Provided you have a suitable commute (speeds <41 mph), Pulse and Glide plus Warp Stealth in the Prius II for maximum FE … - CleanMPG Forums will help. It was used to achieve Hybrid drivers to push Prius to the limit.

http://priuschat.com/forums/gen-ii-...angauge-best-threads-mileage-improvement.html is good for starters. I have a ScanGauge myself and it's been somewhat insightful, but I never went in w/any illusions that it would there'd be any "payback". If you're going to be getting a pre-06 Prius (or an 06 or later that's stripped down enough where there's no backup camera), CAN-view index might be a decent investment if you're interested in what's going on. I have the higher res MFD so I can't use this w/o a second LCD.

BTW, you posted in the wrong area, unless you're asking about the upcoming Prius v (for versatile). I've already flagged your message to be moved.

 

I used to buy a motorcycle and then spend a ton of money trying to turn it into the bike I wanted.

Then one day my wife asked, "Why don't you just buy a motorcycle that has all the stuff that you want to begin with?" I'm sorry to say that idea had never occurred to me.

The same thing goes for you and your Prius. Why don't you just get a nice used BMW or something? The Prius is just about perfect the way it is . . . for what it is.

 

My recent reading seems to indicate that a boattail is the most bang for the buck in terms of reducing drag (thus increasing mileage and performance). No personal experience...yet.

76 hp is for the ICE engine only. Chasing horsepower is a vain pursuit anyways. Most people who brag about horsepower have no idea what it does for them. Just how fast do you want to drive? If you want to brag, use the 295 ft-lbs (or whatever it is) of torque the motor puts out.

Good luck.

 

You can add an electric drive to the rear wheels and some additional battery capacity as is done in the Highlander Hybrid AWD. This will give better performance, but unless you do it as a "Plug-in" will slightly reduce MPG due to the extra weight. It does have the added advantage of better traction in slippery conditions.

JeffD

 

I would think aerodynamic concerns have little impact below 70 kmph (50 mph), however you would be hauling the mass of the boat-tail around all the time, on a Prius's scale weight this could be a factor.

A boat tail that had real effect would need to add about another half of a car length, and would likely still be a turbulent shape anyway, and there may be other consequences driving in fast open environments due to wind gusts making the shape unstable or worse, giving lift. I think overall the idea has doubtful providence except for particular high speed controlled runs.

Interestingly the shape of Prius is conducive the the findings of Wunibald Kamm the inventor of the Kammback design. In following this aerodynamic principle the tail should be cut off where it has tapered to approximately 50% of the car’s maximum cross section, which looks about right on Prius. Kamm's conclusions saw this as the best drag compromise in the convenience of a car shape, and its been a popular design factor for decades.

A good rule of thumb is to use Hp for max velocity and torque as a value of acceleration. I would assume what he is looking for is torque.

Actually a hybrid design offers rather a lot here, in that combustion engines offer rather miserable torque low down in rpm, where electric drives often give near their maximum, conversely where electric drives drop off at speed (where overtaking might be important) IC engines are at or near their best.

 

A PHEV kit will improve mpg, but will cost you more and worsen handling.

most handling mods will lose you mpg, and cost you money.

any "fuel atomizers" or "special air filters" won't improve power or economy, but will cost you money.

In short, the prius is optimised to balance power, economy, and driving dynamics. the third gen is better than the second in all three respects. if you are serious about your list of mods i would use the money to get a gen 3 instead.

 

Hi ZFL,

Sorry, but your research is faulty.

Warm air intakes reduce power, and may improve mileage, but tests on the Prius have shown no difference.

The Prius, in ALL trim levels comes with alumimum wheels. There are lighterweight forged aluminum wheels, but they mount larger tires which pretty much negate the advantage of the ligher wheel weight.

The Prius has an aluminum hood and hatch lid already. The advantage of carbon-fiber will be negligable, as these parts are already very low mass.

The Prius already uses top of the line NGK Iridium spark plugs, which are very effective, and last a looooong time.

The 2nd Gen Prius uses a torsion beam rear suspension. The main handling complaint with the car is not oversteer, but understeer. This can be helped with various handling parts, first off is the BT Tech (or various knock-off) rear chasis stiffening plate. The stiffening plate is cheap enough, and has dramatic improvement on the controlability of the 2nd Gen Prius in high side-force maneuvers and enviorements. Understeer at high speed turns still happens however with just the chasis stiffening plate. A strut bar is and front stiffenning bracket are probably needed to help this. There are others with lots more experience about this on here.


As to mileage improvements, A pillar turbulators, grill blocks, and flush hubcaps, and rear view mirror turbulators are what I had on my Gen 2. You might check in at ecomodder.com for lots of ideas. The flush hubcaps probably has the best effect. But, these are not for mountain driving, of course. I did 70 mpg tanks a few times commuting in Suburban Chicagoland - 1/3 highway, 2/3 secondary road.

100 mpg will require a PHEV setup. Which might not be economically a good idea. The people who are using these are pioneers, and cost is not the main object. Eventually, these systems will become cheaper, but right now they are developemental.

Mobil 1 synthetic is good. I am not so sure you can go with the 0W20 like the third gen, I used the 5W30 with good effect.

Now as to your 76 HP comment, the 2nd Gen Prius is rated at 110 hp, and has acceleration similar to a automatic transmission car of the same size with 130 HP. This is because of the electric motor has a better torque characteristic for automotive application than internal combustion engines. As well as the lack of shifting time.

The idea of a Hybrid drive, is that in typical application, a car's average power is quite low. If one can run that engine closer to that average power , and store energy when the driver is not requiring it to go into the vehicle motion, then a much more efficient conversion of chemical to vehicle energy can occur. This gets complicated, but suffice it to say, an engine with the power closer to the average used by the car, is more efficient. Using a high powered engine at low power is VERY in efficient.

 

The only way to get to 100 MPG is to keep the engine from running.

The EV mode switch can be useful to keep the engine from idling while stopped, such as when the engine idles to increase coolant temp for cabin heating, and under very, very limited circumstances while traveling. If used with impunity, it will decrease fuel economy. There are online instructions for installing the EV switch for free -- no need for a $89 item.

The engine block heater is about the only thing on JuicedHybrid that has a chance to increase your fuel economy. The rest: K&N filter, these ignition things, will not have a material impact.

Plug-in conversion kits provide a way to (1) keep the engine from charging the hybrid battery and (2) transfer electrical energy from an external source to the wheels. The Enginer kit is the cheapest way to get to 100 MPG, but it does require work on the part of the user. The cost of the Enginer kit is dominated by the batteries. As the cost of lithium iron phosphate declines (nearly $1/amp hour now), and/or the price of gas increases, the cost/benefit increases. I expect future improvements will be driven more by the Enginer user community than by Enginer. The other kits like Hymotion or Plug-in Supply have the capability to go well over 100 MPG, but are much more expensive. None have the ability to pay for themselves under current conditions.

 

i once ran a roadrace with a young man not unlike yourself. he spent the night before doing shots and telling everyone how fast he was and hoe no one else stood a chance. he showed up the next morning in high top sneakers, took off so fast he was out of sight of the rest of the pack. when we hit the end of mile one, he was doubled over on the side of the road. never heard from again. all the best!

 

Toyota charges $22,000 for a car that gets 50 MPG, if they could charge you $22,050 for 55 MPG don't you think they would? Many of the 'snake oil' claims are refuted all over the internet, just search.
There ARE batteries that increase the mileage, but sadly most never pay for themselves in normal usage.

[ame=http://en.wikipedia.org/wiki/Snake_oil]Snake oil - Wikipedia, the free encyclopedia[/ame]

 

No, the Scangauge gives YOU more information. You may use that to drive more economically, but it is up to you.