Hybrids in Hilly Terrain

[Morris Minor]

I now live in very hilly area: narrow roads, very curvy, hairpins, steep gradients, speeds rarely above 35mph.

Wear & tear is high: you spend a lot of time on the brakes as you slow on a downhill, or for a curve, or for a stop sign at the bottom of a hill. And of course the transmission never gets a chance to stay long in any ratio; it's all upshifting & downshifting.

So things are very different from the flat suburban environment I was in before, & I've noticed my fuel consumption has increased.

Would a hybrid make sense? I know the stereotypical use case for them is that, to maximize their advantages, their best application is for heavy  stop-start urban traffic. But I'm thinking one would also work here: torquey electric motor for low speeds & all that regenerative braking.

Thoughts?

[Payman]

I now live in very hilly area: narrow roads, very curvy, hairpins, steep gradients, speeds rarely above 35mph.

Wear & tear is high: you spend a lot of time on the brakes as you slow on a downhill, or for a curve, or for a stop sign at the bottom of a hill. And of course the transmission never gets a chance to stay long in any ratio; it's all upshifting & downshifting.

So things are very different from the flat suburban environment I was in before, & I've noticed my fuel consumption has increased.

Would a hybrid make sense? I know the stereotypical use case for them is that, to maximize their advantages, their best application is for heavy  stop-start urban traffic. But I'm thinking one would also work here: torquey electric motor for low speeds & all that regenerative braking.

Thoughts?

Weren't you driving a Prius?

[Morris Minor]

Weren't you driving a Prius?

I was until about two years ago - it's now owned by my daughter out in Texas.

[Payman]

I was until about two years ago - it's now owned by my daughter out in Texas.

Well, being one of the few here with real world hybrid experience, you're probably the best qualified to answer your own question.

[FoMoJo]

A forum discussion that may be informative...http://gm-volt.com/forum/archive/index.php/t-6989.html

[MX793]

Hybrid would certainly save on brake pad wear.  That said, while you will be reclaiming energy going down the hills, you'll be consuming it again when you inevitably go back up them on your return trip.  And your consumption should exceed your regeneration.

Most any modern, fuel injected engine I'm familiar with will basically shut the fuel injectors off under engine braking.  You should be getting pretty good mileage going down those hills unless your gearbox is holding a high gear or decoupling the torque converter and idling.  Manually selecting a lower gear, or just holding gear, should help fuel economy in that case.

[Morris Minor]

I'm intervening far more with the gear shifting that I did. The G37's transmission is not terrific at the best of times and it gets completely discombobulated in the terrain here. So I shift it in to "S" mode and hold gears on the downslopes to get engine braking. Nevertheless the brakes are taking a beating like they never had when I was in the suburbs.

So I was thinking the downhill regen would be a plus. However a hybrid's ICE still has to lug the motors & battery pack on the uphills.

[Tave]

Brakes are designed to bring a vehicle from 100mph  to zero multiple times a day for over 50,000 miles. The hills'o'Georgia shouldn't be having any noticeable impact on wear.

One common mistake people make while braking is to be too easy with them, causing them to both stay on brake for longer than necessary and give their strongest pulse at the end of the maneuver. What you want to be is firm, brief, and "lifting off" as opposed to "digging in."

Get a manual and don't worry about the brakes. 

[Laconian]

My brother drove his Prius all around central WA, which is extremely hilly, and got great fuel economy.

[CaminoRacer]

I always get fantastic fuel economy when I drive through the Rockies.

[giant_mtb]

Interesting question. Interesting results.

[12,000 RPM]

Brakes are designed to bring a vehicle from 100mph  to zero multiple times a day for over 50,000 miles.

Not on a street car. I don't do that and my front rotors are toast after about 20% of that mileage.

I think this application would be perfect for a hybrid. There is a ~4 mile loop around my subdivision with no stop signs or lights, but a shit load of hills. I've got as much as ~50MPG in the G on that loop on fresh MPG reads. With what he will capture from regen he should be able to sip fuel and save his brakes. I think the hybrid move is the right one.

[giant_mtb]

Not on a street car. I don't do that and my front rotors are toast after about 20% of that mileage.

Rotors every 10k?  You really do drive like an asshat, don't you.

[Soup DeVille]

Dragging brakes to maintain speed down a hill is one of the most surefire ways of burning them out quickly. Hell, it's one of the best ways to experience sudden brake failure.

There's a huge difference in the heat/cool cycle between a sudden stop from any speed and a slow grind down a hill.

[Soup DeVille]

Rotors every 10k?  You really do drive like an asshat, don't you.

Either he's really exaggerating, or you're 100% correct.

[shp4man]

A hybrid would work nicely. Plus, you could feel completely superior to those Neanderthals that drive lifted 4x4 diesel trucks. 

[Morris Minor]

A hybrid would work nicely. Plus, you could feel completely superior to those Neanderthals that drive lifted 4x4 diesel trucks. 

Lots of trucks around here. I'd have to put an NRA sticker on the back of my hybrid to ward off harassment from the wispy-beard-&-meth-mouth crowd.

[giant_mtb]

Either he's really exaggerating, or you're 100% correct.

Probably both.

[MX793]

Dragging brakes to maintain speed down a hill is one of the most surefire ways of burning them out quickly. Hell, it's one of the best ways to experience sudden brake failure.

There's a huge difference in the heat/cool cycle between a sudden stop from any speed and a slow grind down a hill.

Reminds me of a vacation I took in Gatlinburg a couple of summers ago.  We were staying at a place right on the edge of town, right at the entrance to the Smoky Mountain Park.  All those lush pines, but all you could smell was burning brake pads from people riding their brakes down the long decent from the mountains into town.

[AutobahnSHO]

Reminds me of a vacation I took in Gatlinburg a couple of summers ago.  We were staying at a place right on the edge of town, right at the entrance to the Smoky Mountain Park.  All those lush pines, but all you could smell was burning brake pads from people riding their brakes down the long decent from the mountains into town.

I've driven there and it's 5x worse between Park City and SLC, Utah. Sometimes you get inexperienced semi drivers that smoke up the entire canyon.

[Xer0]

Just get a manual and engine that shit down.

[Soup DeVille]

Just get a manual and engine that shit down.

Don't need a manual for engine braking, why do people keep repeating this?

[MX793]

Don't need a manual for engine braking, why do people keep repeating this?

Engine braking in most autos I've driven is far reduced compared to any MT car I've own.  If I let off the gas in my Jetta to try to engine brake, it will either upshift or outright decouple the torque converter so the only "braking" I get is from the rolling resistance of the wheels.  Even if I put it in Tiptronic and force it into a lower gear, the amount of braking is far less than I'd get out of any MT car I've ever driven.  I have to shift down into 2nd at 40 mph to get the same kind of engine braking that I'd have gotten in 3rd or even 4th in MT cars I've owned.

[mzziaz]

Bolt and the new Leaf regen makes brake wear a non issue. 

[veeman]

Don't need a manual for engine braking, why do people keep repeating this?

Engine braking in most autos I've driven is far reduced compared to any MT car I've own.  If I let off the gas in my Jetta to try to engine brake, it will either upshift or outright decouple the torque converter so the only "braking" I get is from the rolling resistance of the wheels.  Even if I put it in Tiptronic and force it into a lower gear, the amount of braking is far less than I'd get out of any MT car I've ever driven.  I have to shift down into 2nd at 40 mph to get the same kind of engine braking that I'd have gotten in 3rd or even 4th in MT cars I've owned.

Somewhere I've read  few times that it's better to wear out your brakes faster than it is to put stress on your transmission from engine braking.  Is this not true?

[AutobahnSHO]

Somewhere I’ve read  few times that it’s better to wear out your brakes faster than it is to put stress on your transmission from engine braking.  Is this not true?

Hard shifts would be bad, it is indeed easier to change brakes than transmissions.

But if you shift properly (not slamming gears or massive downshifts at high RPMs) transmission should be fine. With bicycles and cars- always downshift before you need to.

[Soup DeVille]

Engine braking in most autos I've driven is far reduced compared to any MT car I've own.  If I let off the gas in my Jetta to try to engine brake, it will either upshift or outright decouple the torque converter so the only "braking" I get is from the rolling resistance of the wheels.  Even if I put it in Tiptronic and force it into a lower gear, the amount of braking is far less than I'd get out of any MT car I've ever driven.  I have to shift down into 2nd at 40 mph to get the same kind of engine braking that I'd have gotten in 3rd or even 4th in MT cars I've owned.

Yes, absolutely you need to shift down manually, be it tiptronic (useless in all forms), or regular AT.

Is it less? sometimes. Do you sometimes need to hit the real brakes to downshift, then let it ride? Yes; this is basic stuff though.

Who cares what gear you need to put it in? Unless you're going under about 10 MPH, there will be a gear that will hold you at a safe speed

[Soup DeVille]

Somewhere I've read  few times that it's better to wear out your brakes faster than it is to put stress on your transmission from engine braking.  Is this not true?

It's absolute balderdash.

Dangerous and irresponsible shite.

[Morris Minor]

Bolt and the new Leaf regen makes brake wear a non issue. 

It's definitely an issue here: I know my brake rotors are starting to warp.

[MX793]

Yes, absolutely you need to shift down manually, be it tiptronic (useless in all forms), or regular AT.

Is it less? sometimes. Do you sometimes need to hit the real brakes to downshift, then let it ride? Yes; this is basic stuff though.

Who cares what gear you need to put it in? Unless you're going under about 10 MPH, there will be a gear that will hold you at a safe speed

People tend to look at you funny when your car is winding out at 5K+ RPM as you coast to a stop?  There are a number of hills around here where I can downshift from 6th to 5th or 4th in my Mustang and hold speed down the entire hill without touching the brakes.  My VW won't, even when manually shifted into the lowest gear possible for the speed I'm traveling.