September 25th, 2008

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10:23 pm - unlearning a lifetime of driving habits
So, I recently bought a Chevy HHR because Jiffy Lube destroyed my beloved Mighty Neon.

The HHR was billed as getting 22MPG city / 28MPG highway. I've always tended to get significantly better mileage on my vehicles than the EPA ratings; I keep my vehicles in excellent shape and I understand where the powerband is on the engine.

So I was pretty shocked when, after the first couple of weeks, the HHR was reporting about 17MPG average. Ouch! And wtf?

After that shock, even though I felt like I knew better, I tried driving like most people do when they are trying to save gas - I babied the throttle. Creeping off the line, accelerating very lightly, et cetera. As I've always told people, this isn't the great idea they think it is - if you're accelerating outside the engine's powerband, you're wasting gas. Unsurprisingly, my couple of weeks spent babying the throttle didn't do me any good. I got up to about 18 or 19 MPG, but that was with SERIOUSLY grandmothering the hell out of EVERYTHING - not just accelerating slowly off the line, but also cruising so sedately that people kept diving in ahead of me. Very little improvement in economy, with a SEVERE decrease in the entire driving experience.

So I got thoughtful, and I flipped the HUD on the car to "instant MPG" mode and really paid attention. And I figured out what was biting me in the butt: modern (meaning within the last 2 or 3 years) automatic transmissions are very different from the ones I grew up with.

Traditional automatic transmissions leave the car in gear when you idle. What this means is, when cruising at a relatively stable speed, the best fuel economy you can get is to feather the throttle precisely to what's needed to keep the car moving at that speed - the less surging, the better. Trying to coast by taking your foot off of the gas entirely is generally a mistake, as the drag of "engine braking" with the vehicle still in gear will slow you down rapidly, so accelerating back again is a net waste of fuel.

The automatic in the HHR, however, actually puts the vehicle in neutral when your foot is off the gas. This makes for a very different picture when it comes to maximizing fuel economy: suddenly, coasting and accelerating makes a lot more sense. You have to remember, again, that an engine is most efficient inside its powerband: when it is accelerating pretty strongly. So in the case of a vehicle with a transmission that goes completely neutral when your foot is off the pedal, the most efficient driving profile becomes one in which you accelerate smoothly but fairly strongly off the line to cruising speed, then take your foot off the throttle until you start to slow down, then accelerate again fairly strongly but briefly, then coast... wash, rinse, repeat.

It's an odd way to drive, to my sensibilities. And it requires considerably more skill and attention: the idea, after all, is not to make it obvious to other drivers that you're accelerating in surges; you don't want to vary your speed more than 1mph or so while you're "cruising". But the results of trying it speak for themselves: I went from averaging 17-19 MPG to and from work to averaging 24 MPG on the same route.


(21 comments | Leave a comment)


[User Picture] From: billyfleetwood
Date: September 26th, 2008 - 04:54 am
I was never good enough at the math to take engineering seriously after a point, but my years of summer engineering camp taught me one thing...if you can't find the most efficient way to do something, it's not worth doing.

The last car I owned was a 91 honda civic. I think at the time it was rated somewhere in the high 20's, but I could usually coax 35 mpg out of it. And that was mostly city driving. I still think i should have bought an entire fleet of those things.

[User Picture] From: staringgoldfish
Date: September 26th, 2008 - 07:09 am
Jiffy Lube destroyed my beloved Mighty Neon.

That sounds like quite a rant unto itself.

Last year the local Pro Lube - think Jiffy Lube without the capable staff - changed my oil, sold me a new serpentine cable and battery and did something to the security system that killed my stereo so bad I had to take it to the GM dealership and get it reset. Which bit, because we were supposed to have left for Minneapolis about two hours before we actually left town.

Pro Lube sucks.

[User Picture] From: jimbojones
Date: September 26th, 2008 - 04:38 pm
see reply to tehonyx, below.

[User Picture] From: ravenword
Date: September 26th, 2008 - 10:49 am
Oh noooo, Neon! A nation mourns. :-(

We lost a workhorse of a Camry (15 years old! I was looking forward to its Sweet Sixteen party when it would be old enough to drive itself) after the neighborhood mechanics worked on it last year. Had it serviced, all fluids changed/topped off, then two days later it's completely out of coolant and fatally overheats in rush hour traffic. We can't prove that they fucked it up, but it had never had any kind of problem with overheating or leaking before.

I don't think I've ever ridden in a car with one of these newfangled automatic transmissions. I'm used to cars creeping forward when they're in D even if I'm not hitting the gas, which I assume is not the case if the thing defaults to neutral?

[User Picture] From: jimbojones
Date: September 26th, 2008 - 02:05 pm
No, the HHR doesn't creep. It's worth noting that it isn't entirely at neutral when the car isn't moving, though; for example it doesn't roll backwards like a stick would if you're stopped at a light on a hill.

I confirmed to myself once and for all that it does go to neutral at cruising speeds, though, by actually PUTTING the stick in neutral. Nothing happens - no thunk noise, no change in speed, no change in instant MPG reading. Also, if you accelerate firmly from off-throttle at cruise speeds, the engine tachs up to 3000 or so (right in its powerband) immediately before (pretty gently) clutching back in.

I have to say the oldschool type trans is more fun to drive; the HHR is actually pretty fast (I got the upgraded-everything model with sport-tuned blah blah blah) but the throttle response doesn't ever feel very crisp. But, now that I know HOW to drive it for economy, the efficiency results speak for themselves. Semi-highway driving (average 45 mph speeds with fewer stoplights than in-town) the new way gets me about 35 MPG. You can't really argue with that in what amounts to an SUV!

[User Picture] From: theonyx
Date: September 26th, 2008 - 12:21 pm
What's Jiffy do, forget to put oil in the thing after an oil change?

[User Picture] From: jimbojones
Date: September 26th, 2008 - 01:59 pm
No; they used an extractor instead of dropping the plug (vacuuming out the old oil through the dipstick tube) and they MISSED the bottom two quarts of oil. Then they dumped 5 quarts more oil IN.

Then I drove to Alabama.

In addition, they completely fucked up my air cleaner assembly (just kinda half-ass crammed HALF of the intake into the box and bolted it together crushed) and did not top off my power steering fluid (which was low enough to make very audible complaints when the wheel was turned at stop - and for the first time ever in my ownership of the car, I might add).

I have pictures of the (FILTHY, because, you know, the bottom 2 qts they didn't extract were WHERE ALL THE SLUDGE WAS) extremely overfilled crankcase and of the abomination they did to my air cleaner assembly. With any luck, I will force them to pay for a new engine for the Neon, but I can't just walk to work in the meantime, hence the HHR.

[User Picture] From: theonyx
Date: September 26th, 2008 - 02:07 pm
I just died a little inside.

They'd better pay for the fucking engine, although they might try to throw some sort of legal-ese at you based on what you signed when you got service. I'd imagine you could still get a claim paid due to gross negligence or "failure to provide service".

In other news, I'm back from my India trip, and I'm finally moved into my new place. I'm feeling a visit (one way or the other) sometime soon, now that my life won't be freaking hectic. Unfortunately, the trip I spoke of in October was made official, so I won't be at the wedding, but I still wanted to try to see you guys before the big day.

[User Picture] From: jimbojones
Date: September 26th, 2008 - 04:20 pm
Damn @ no wedding-presence! Of course you are always welcome.

Unfortunately now your choices of sleeping arrangement are:

1. living room (shared with approximately your weight in dogs)
2. upstairs room (shared with weight equipment and a cat)
3. um. floor in the reading room? or the office i guess. but jeer killed my sleeping bag MONTHS ago
4. sleeping in the street like a hobo

The good news is, Chris and Karen have some sort of plan to take a picture of Chris standing over a bloody hobo with a hammer and a tophat, so maybe #4 can work out to everybody's benefit.

I'll supply the vodka!

[User Picture] From: theonyx
Date: September 26th, 2008 - 04:34 pm
It'd be funnier with a cane, bow tie, tophat. Bonus points for having a bag with a dollar sign on it in the other hand.

Hrrmm. None of those options are terribly compelling given my allergy to pet dander or desire for a closed door so I can jerk off on everything in the room. I guess I could avoid the jerkfest for one weekend, though. What happened to the couch in the reading room? It was a bit short for me, but worked.

Also, when things aren't so hectic with you and the hobo situation is under wraps, I'd like you have you peeps down to see the new place. I want to try to have a poker game at the new place sometime soon for the local peeps. Ideally, I could time it when you guys could roll down here for a couple of days.

[User Picture] From: jimbojones
Date: September 26th, 2008 - 04:37 pm
Well you could always sleep in Chris' bathtub then. Everybody's happy! Except Chris, first time he sees what his bathroom looks like under a blacklight.

The couch in the reading room went bye-bye. Hm; now that I think about it Chris should still have an inflatable mattress. Or if he shitcanned his, one could be procured.

[User Picture] From: theonyx
Date: September 26th, 2008 - 05:29 pm
Yeah, if he still has an inflatable mattress, crashing on that in the living room would prove to be sufficient.

[User Picture] From: theonyx
Date: September 26th, 2008 - 05:30 pm
*reading room

[User Picture] From: pantsnotneeded
Date: September 26th, 2008 - 09:29 pm
I'll look for it this weekend.

[User Picture] From: clme
Date: September 29th, 2008 - 01:33 am
I prefer to jerk off on everything in the room with the door open.

Jim has a decent sized house though, so make sure you stock up on electrolytes. I damn near dehydrated myself last year. Of course the cat didn't seem the least bit phased... perhaps it has witnessed this behavior before?

Honestly though, I couldn't even bring myself to revive the tradition of fucking in Jim's bathroom. I had to settle for sleeping naked in Jeer's bed.

I'm not making it in October :-( I had to move vacation time to a different week, so I'm going to St. Louis and parts of Arkansas with the wife then instead.

[User Picture] From: clme
Date: September 29th, 2008 - 01:38 am
Oh yeah... I bet they'll settle for value of the car if its less than replacing the engine. Make sure you go in with the KBB values. They didn't keep up their end of the contract either, and that can help a lot.

I've worked at oil change places that double-gasketed the oil filter, or put oil in the radiator instead of the engine. In both cases there were settlements, but those were complete engine failures. We didn't do any of that 'vacuum it out' shit though. That just seems like a way to avoid having to retap drain plugs when assholes overtighten.

My grandfather had his oil changed in an old Jeep Grand Cherokee and they never put fluid in. He drove out of the garage, got out into the street, and then noticed the light. They replaced his engine.

[User Picture] From: clme
Date: September 29th, 2008 - 01:40 am
hastyLJedit: WEREN'T complete engine failures. I typed that wrong above.

[User Picture] From: marys_second
Date: September 26th, 2008 - 12:46 pm
That's an impressive increase.

[User Picture] From: herbaliser
Date: September 26th, 2008 - 04:31 pm
I keep tripping over your wording. For example, we borrow Reg's parents SUV to go camping, and at highway speeds (60+mph) if I take my foot off the gas going downhill, nothing happens. I mean, it guess it stays in gear, going about the same speed, doesn't speed up like when I put my own car in neutral. It starts to slow down when the hills level out.

[User Picture] From: jimbojones
Date: September 26th, 2008 - 04:35 pm
In the HHR you are no shit IN NEUTRAL when you take your foot off the throttle at highway speeds. You will speed up if you are going down a hill. If you actually put the shifter in neutral, nothing detectable happens - no thunk sound or feeling, no change in speed, no change in instant MPG reading.

Reg's parents' SUV sounds like it has a regular type auto trans. According to Chevy's brag sheets the trans type in the HHR (and in the Aveo) is a pretty new and innovative deal.

[User Picture] From: clme
Date: September 29th, 2008 - 01:43 am
That would actually improve handling in slick/ice conditions. One of the first things I was taught about driving in slick conditions was to slam the gearshift in neutral when slipping (assuming its not a column shifter) and turn the wheels the direction I want the car to go. Most shifters dont require a button to be pressed in order to shift from drive to neutral.

(Its not that column shifters cant shift into neutral, its that I cant do it fast; maybe its me).

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