Hi all,
I read recently that some hobbyists had modified their Priuses (Prii?) to coast as much as possible and thereby achieved 200 mpg on the racetrack.
My questions are:
Thanks.
That 200 mpg is only for the first 10 miles on any trip, and after that, their mileage is the same as any other Prius.
Basically they spent around $30,000 in parts to add additional batteries and an internal charger. The batteries only lasted for the for the first 10 miles, then they ran out and the regular Prius system took over. Add the cost that a regular consumer would have to pay someone to design and install the system and it could be an additional $40,000 on top of the base cost of the car. That's kind of a lot of money to spend to get improved mileage only for the first 10 miles of a trip and then regular mileage for the rest of the trip, which is why auto manufacturers have not yet tried to commercially market the "booster batteries".
Have you heard of Oklahoma Overdrive? Popularized when the dust bowl refugees practiced principle #2 whenever they could on their journey to California -- but especially during downhill runs in the mountains.
You can do it, but it frowned upon by the authorities.
Too bad that coasting is illegal on the roads. This is a law that I disagree with and I coast all the time in my Jeep 5 spd. Tougher to do in the Sienna.... Tomes
I don't believe you. Tell us which law and which state. Even if it exists, I bet such laws are not universal.
No, it can not be applied to a manual stick shift car. It can't be applied to ANY car that is driven on the streets and highways because it is ILLEGAL to coast in Neutral or with the clutch pedal depressed.
Yes, the theory works well, no the practice doesn't work at all. There are huge safety implications with cars rolling along down hill doing 70 in Neutral.
Why do you think this is a valid statement? In any situation, protecting yourself involves braking, not accelerating.
OK, tell us why it is illegal to coast in Neutral, and provide ANY state's vehicle code that says it is OK to coast in Neutral. (Coasting in Neutral and coasting with the clutch pedal depressed is the same thing, by the way.)
California Vehicle Code
21710 - Coasting Prohibited The driver of a motor vehicle when traveling on down grade upon any highway shall not coast with the gears of such vehicle in neutral.The only possible reason is that there is an inherent safety issue with operating a motor vehicle in this manner.
Go to
Type in the search box these three words
coasting neutral prohibited
Count of the number of state laws that pop up prohibiting the practice.
Then read a few other articles from the safety publications that pop-up. Then report back. :>)
I can tell you /exactly/ where this law came from, even without a reference footnote on the bottom saying something like "Enacted 1935" (when the first statewide regulations were codified) - remember totally unsynchronized transmissions, AKA "Crash Boxes"? Many cars got synchros as soon as they were invented, but some trucks are STILL sold that way.
Not like the old VW Beetles or MG's that didn't have a Synchro on First, making it a bear to get into first at anything but a dead stop, I'm talking they didn't have a synchro on ANY gear. You either double-clutched, or you matched road speed and RPM's and slid the gear shift home for the next gear at the right moment every time, or you simply didn't go anywhere. If you sat there and ground on them at every shift, you'd quickly destroy the gearbox.
Especially in a hilly state like California, there were too many instances where a heavy truck or car shifted out of gear on a hill and started coasting nice and easy... Then the hill got steeper...
Then the brakes started fading or weren't strong enough for the hill and load, and they started picking up speed. (Remember all-mechanical brakes? And later hydraulic drums?) Then they tried to shift into gear while moving for some engine braking and simply couldn't get the tranny to go back into gear (GRRRUNNNNNCH!)...
Followed moments later by the vehicle doing one of the following: A. Too fast for the curve, Over the edge of the cliff. B. Too fast for the curve, Smack into the side of a hill. C. Too fast for the rough road, Lose control and roll or crash. D. Unable to keep to their side of the road in a right-hand curve, collect a few more unfortunate souls going the other way, then see A B or C. E. Bounce off the side of the hill or the old steel guardrail on a left hand curve, lose control, cross the line, hit a few cars full of people, then see A B or C.
In a non-synchro box, once those gears on the countershafts stop spinning while you are underway, you play hell getting them spinning again. When you are on the verge of losing control anyways is NOT the time to try and play with the gears. You have about five seconds to do everything right, in the right order, and get it together in time to save yourself (and a bunch of innocent people that will be in the way) - Tick... Tick... Tick... Tick...
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Good, informative explanation Bruce!
BTW, shifting an automatic transmission into neutral and then back into gear at 60 MPH doesn't exactly help its durability.
I am not going to go look it all up, but we had this discussion at length in the Jeep NGs. Folks actually were pulled over for it. The evidence stated was state/province, not national.
So what you're saying is that the law came into effect because of cars that, unlike today's, did not have syncro on each gear.
Therefore the law is inappropriate today on anything but antique cars.
Do the same thing I do when downshifting for a hill at speed - tap the gas a bit as you slide it into '2', so the speeds are better matched and stresses lower. Works on slushboxes just like it does on a stick.
Next lesson is Brake Float, or how to save your suspension when you run across an unexpected 'DIP' at about double the usual sane speed...
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Not really...synchros aren't magic, they cannot 'sync' gears which are wildly out of sync...so you'll just end up trying to ram the lever into a low gear and the synchro preventing it as you sail gaily through the guardrail.
Uh, no it's not. Coasting in neutral and coasting with the clutch pedal are different. Please proviode ANY state's vehicle code that can't tell the difference between coasting in newtral and coasting with the clutch depressed. Then describe how to shift gears without coasting with the clutch depressed (or without coasting in neutral).
It's still not a convincing argument, because
A. I've never seen a modern car refuse to get into gear, although I have also driven Japanese cars, maybe that's why.
B. In a dangerous situation, steering and brakes are still enough to drive safety.
As if you know so much. Better for you to go back to school.
In fact it would be better for you to just shut up and listen to others that know much more than you do.
This manouver makes sense but I doubt if anyone who is putting the car into neutral knows to do this on an automatic, and I doubt if anyone thinks of this if they shift into neutral at speed and then re-engage the transmission.
And even if the synchros allow shifting, with such a big difference between engine speed and output shaft speed, the synchros will be worn out pretty quickly.
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