MPG vs. cruise control - Toyota Prius Forum : Prius Online Toyota Forums
User Tag List

 
LinkBack Thread Tools
post #1 of 9 (permalink) Old 04-04-2007, 03:14 AM Thread Starter
Junior Member
 
Join Date: Dec 2006
Location: Hong Kong
Posts: 4
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Default MPG vs. cruise control

i read, the most efficient way of driving your prius is with cruise control...as it optimizes energy consumption between ICE and electric motor...
question: is it true you get better MPG by using cruise control?
in fact i have learned how to drive w cruise control in dense urban traffic in almost all situations i only use cruise control...or coast...its almost like driving a ship...and you do have to learn how to drive from scratch which is FUN.
when i accelerate from standstill i do it either w batt power or press pedal one third until i can engage cruise control...
generally my MPG is not good becasue i commue short trips only (10-15mins) and my town is rather hilly (hong kong)...i average 44mpg...my prius is 4 months old and has 1400miles...any tips on optimizing MPG in this scenario?

blk dlx PRIUS dec06
blubot is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 04-04-2007, 09:34 AM
Senior Member
 
Join Date: Apr 2003
Location: MO
Posts: 1,434
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Default

While the use of CC early in the learning process of driving the Prius may show some improvement over the initial non-CC driving it's clear that the CC is overly aggressive in maintianing speed and will, in almost all situations, result in lower FE than can be achieved by leaving it off.

The exception is probably steady speed highway/freeway driving where the ability of the CC to maintain a steady speed is superior to that of the driver at long distances.

Evan Fusco, MD
'04 BC/Seaside
Nixa, MO http://greenhybrid.com/compare/milea.../signature.png
efusco is offline  
post #3 of 9 (permalink) Old 04-04-2007, 03:49 PM
Senior Member
 
Join Date: Oct 2004
Location: Dallas TX
Posts: 610
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Default

Seems to me that the Cruise Control in my 2007 Prius is a bit less aggressive than the one in the 2004 I traded. I would still prefer even less CC "DETERMINATION" to get back to the set speed so quickly.

I suppose this is a 'feature' of 'drive by wire.'

♫ Charles Suitt ♪ Dallas TX ♫
2007 Driftwood Pearl - Touring
∞ Package 6 - Option A ∞

Previous Prius: 2004 Package 8
ChasSuitt is offline  
 
post #4 of 9 (permalink) Old 04-04-2007, 04:14 PM
Senior Member
 
Join Date: Mar 2003
Location: Phoenix, AZ
Posts: 884
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Default Cruise Control & MPG

I respectfully disagree...

In cool weather, my classic Prius consistently gets 50+ mpg in city driving (approximately 35 minute commute at 40-45 mph, with traffic lights every half mile) using full throttle starts up to 30-35 mph, and then cruise control exclusively. I usually get 51-53 mph, with an elusive best 56.5 mph on one fill-up last year.

When using throttle only, mid- to high-40's is the best I can do. At least with the older Prius models, the computer (via cruise control) is better at optimizing fuel economy than my right foot.
Phoenix is offline  
post #5 of 9 (permalink) Old 04-04-2007, 04:45 PM
Senior Member
 
Join Date: Apr 2003
Location: MO
Posts: 1,434
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Default Re: Cruise Control & MPG

Quote:
Originally Posted by Phoenix
I respectfully disagree...

In cool weather, my classic Prius consistently gets 50+ mpg in city driving (approximately 35 minute commute at 40-45 mph, with traffic lights every half mile) using full throttle starts up to 30-35 mph, and then cruise control exclusively. I usually get 51-53 mph, with an elusive best 56.5 mph on one fill-up last year.

When using throttle only, mid- to high-40's is the best I can do. At least with the older Prius models, the computer (via cruise control) is better at optimizing fuel economy than my right foot.
While individual cased may vary this is absolutely b/c of the driver's effort/ability/concern about getting the best FE.

This is an objective/mathematical/physical thing much more so than an opinion thing.

Hobbit's research on the 2G Prius has clearly shown peak fuel efficiency to be during ICE RPMs b/w 1700-2300rpm with a slight peak around 1850rpm. Using CC even on slight hills it will aggressively accelerate to or above even 3000rpm. It is incapable of initiating Pulse & Glide, clearly the most fuel efficient way to drive the Prius.

All this said, there are stretches of road where I use CC to maintain speed b/c I simply don't feel there is much if anything I can do to improve on the FE I'll get over the CC and without strict attention may do slightly worse. AND, your driving comfort/style/preferences are clearly as important as FE here. If you're not equipt to monitor ICE RPM, battery SOC, don't want to use that much mental energy to maximize your rate of acceleration and extended glide distance, then using CC is a great idea. Or if you're on a stretch of road where doing those things might seriously impair the flow of traffic, then by all means use CC.

But, there is no question in my mind or those who routinely achieve 'hypermiler' mpg that not using CC is by a long shot superior in most situations to using it. Again, I don't want to come across as argumentative, but this is very much something that makes sense if you consider the physics of maximizing FE.

Evan Fusco, MD
'04 BC/Seaside
Nixa, MO http://greenhybrid.com/compare/milea.../signature.png
efusco is offline  
post #6 of 9 (permalink) Old 04-04-2007, 07:57 PM
Senior Member
 
Join Date: Nov 2004
Location: upstate NY
Posts: 310
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Send a message via AIM to drash
Default

I rely on a constant pressure on the Prius gas pedal which is extremely fatiguing if done for an extended period of time because it is so sensitive. I use energy driving to get over 52 mpg at posted highway speeds of 65mph. On some of the hills I do have to back off going down and give it some gas when going up. I also punch it to a little over 50 mpg on the readout as it comes to the bottom of two hills and try and maintain that mpg reading on the way up. Like I said it is very tiring. It does prove a point to myself that, as magical as the Prius is on capturing energy when coasting or braking, it is no match for the rather simple law of conservation of energy.

After I can't stand it no more I'll put the cruise control on 64 mph and let it ride. The cruise control is very aggresive at maintaining that speed.

Following a tractor trailer can get me over the 60mpg figure but at an anxiety level I'm not comfortable with. Visions of high speed debris flying at my windshield kind of wrecks any grandiose schemes of saving gas.

2005 Salsa Red Pearl AI
Engine Block Heater
Michelin X-Ice on 15x6.5 Sport Edition D3 Silver Wheels
Goodyear Assurance Fuel Max on OEM Wheels
drash is offline  
post #7 of 9 (permalink) Old 04-04-2007, 10:04 PM
Senior Member
 
Join Date: Aug 2004
Location: Tampa Bay
Posts: 7,166
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Send a message via AIM to DanMan32 Send a message via MSN to DanMan32
Default

I don't find the CC that agressive. I find that it provides the most efficient acceleration rate.

However, its goal is to maintain a constant speed. In hilly environments, this is not the most efficient way to drive. Instead, one should slow down naturally losing kinetic momentum to potential energy when going up hills, and gain speed converting potential energy to kinetic energy. This is just how a rollercoaster works. If you'll notice, a rollercoaster only gets its energy once: at the beginning of the ride. The rollercoaster slows down at the tops of hills, and speeds up tremendously when it approaches ground level.
DanMan32 is offline  
post #8 of 9 (permalink) Old 04-04-2007, 10:15 PM
Senior Member
 
Join Date: Apr 2003
Location: MO
Posts: 1,434
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Default

Quote:
Originally Posted by DanMan32
I don't find the CC that agressive. I find that it provides the most efficient acceleration rate.
Compared to what? I find that it never provides the most efficient rate of acceleration as it rarely, if ever, uses rpm <2300 and essentially never at/near 1850rpm which IS the most efficient rate of acceleration.

Where you live and the roads you drive on certainly the disadvantages of CC will be minimal. But in the areas I live even on rather small rolling hills the CC is far more aggressive than any 'peak efficiency' numbers that I've ever been able to gather.

Quote:
However, its goal is to maintain a constant speed. In hilly environments, this is not the most efficient way to drive. Instead, one should slow down naturally losing kinetic momentum to potential energy when going up hills, and gain speed converting potential energy to kinetic energy. This is just how a rollercoaster works. If you'll notice, a rollercoaster only gets its energy once: at the beginning of the ride. The rollercoaster slows down at the tops of hills, and speeds up tremendously when it approaches ground level.
That is essentially a pulse and glide techique for hills. However in traffic that isn't always possible and it's more desireable to maintain constant speed for the sake of those with whom one is sharing the road. In that case anticipating hills and initiating acceleration a little early and maintaining the rpm in the 1700-2300 range as much as possible will give great efficiency with little loss of speed.

Evan Fusco, MD
'04 BC/Seaside
Nixa, MO http://greenhybrid.com/compare/milea.../signature.png
efusco is offline  
post #9 of 9 (permalink) Old 04-04-2007, 10:25 PM
Senior Member
 
Join Date: Aug 2004
Location: Tampa Bay
Posts: 7,166
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Send a message via AIM to DanMan32 Send a message via MSN to DanMan32
Default

I suppose it all depends on the hill grade. When I was comparing CC acceleration, I was considering on its operation when you have it preset for say 55, and you resume it at 40 (without going below 24 from the time of cancelation to the resume). Or, I have it set at a lower speed, and have it accelerate at a higher speed.
However, if one was climbing a steep hill, the speed may drop a considerable amount unexpectedly to the viewpoint of the CC, and thus has to apply heavy acceleration than the rate I experience to regain the target speed.
A driver would have to do the same thing if the driver was to maintain speed. However, the driver would anticipate the potential loss as the driver approached the hill, and would thus add pressure to the accelerator before any speed was lost. Or else the driver would allow the drop in speed and deal with it for a while until it leveled off or started decending.

When I have done my evaluations, the fuel consumption was about 20MPG during the acceleration, and pretty much stayed in the range where little electrical energy was leaving or entering the battery. All electrical energy created from MG1 appeared to be delivered to MG2.
DanMan32 is offline  
Reply

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



  Similar Threads
Thread Thread Starter Forum Replies Last Post
Cruise Control River Rat Toyota Prius Technical - Q & A 9 01-04-2006 06:23 PM
Cruise control Viking Toyota Prius - Technical Chat 23 08-13-2004 04:51 PM
cruise control Hep Toyota Prius General Discussion 7 08-04-2004 01:58 PM
Cruise control kit? paul16451 Toyota Prius General Discussion 4 03-26-2003 10:37 PM
Cruise Control Toyota Prius General Discussion 1 05-23-2002 08:33 AM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome