So I dropped her off at the airport this morning and am now DD'ing her car. She's been complaining that she is "only" getting 34mpg in mixed driving in her '14 Koup 2.0/6sp auto. Still as good as her 1.6L Rio and much faster and better in literally every category that can be measured. I filled it up, and have now driven home and to work. I'm averaging 41.1. What the heck woman?
She's got a heavy foot, apparently.
Is she one of those types who accelerates hard from light to light?
In reply to Bob the REAL oil guy. :
She must drive like my wife.
She used to be that way... but she's been driving lighter footed than she used to. That is one thing, the old Alpha in the Rio got 34mpg always. hard on the gas, light on the gas... it didn't care. These newer engines don't like a lot of throttle.
In most cars, general driving style (especially how / when you coast and brake) matters far more for mpg than how fast you accelerate.
In reply to Bob the REAL oil guy. :
I think too light acceleration burns more gas than moderate acceleration and then conserving momentum. I both drive faster and get ~10% better fuel economy on average than my wife.
Drivers than over-slow and jump on the brakes late get worse fuel economy, even if they accelerate slowly.
In reply to rslifkin :
For sure. This thing LOVES coasting. This is the first modern automatic that downshifts as speeds decrease. The first time or two I drove it was a little unnerving. Then I realized that if I had been in my 6spd manual Forte, I would have down shifted in those same spots and engine braked just like it was doing. They've gotten so smart!
In reply to Tyler H :
Yup. Every car has an ideal acceleration rate. Too slow and you run into the "burning half as much gas for 4 times as long" problem of getting up to speed. Too fast and you're getting into power enrichment and high RPM and losing efficiency.
Ian F said:Is she one of those types who accelerates hard from light to light?
My wife likes to do that and the wonders why I can beat her mileage number in her car.
I can get 29-30 in my wife car vs her 25-26 lol.
My wife gets 14 mpg in her vehicle. When I drive it, I also get 14 mpg. #suburbanlyfe
rslifkin said:In reply to Tyler H :
Yup. Every car has an ideal acceleration rate. Too slow and you run into the "burning half as much gas for 4 times as long" problem of getting up to speed. Too fast and you're getting into power enrichment and high RPM and losing efficiency.
Which is why I love the Eco Bubble thing on my Volt. It's running an electric motor, so apples to oranges, but if you accelerate/brake in the way the car trains you, your range goes WAY up. It would be nice if gas cars had a similar modern efficiency meter to help train drivers.
My dad got horrible mileage on all his vehicles because he varied the throttle constantly. He wouldn't hold the pedal steady. Drove me nuts to ride with him.
mazdeuce - Seth said:rslifkin said:In reply to Tyler H :
Yup. Every car has an ideal acceleration rate. Too slow and you run into the "burning half as much gas for 4 times as long" problem of getting up to speed. Too fast and you're getting into power enrichment and high RPM and losing efficiency.
Which is why I love the Eco Bubble thing on my Volt. It's running an electric motor, so apples to oranges, but if you accelerate/brake in the way the car trains you, your range goes WAY up. It would be nice if gas cars had a similar modern efficiency meter to help train drivers.
That would be handy! 
But seriously, they kinda do. A lot of cars have instantaneous fuel economy gauges, and I've noticed that I'll play the MPG game when I have it up on the display. The Ford Fusion hybrid actually gives you a score after each drive on how you did.
I have a friend with a Fusion Hybrid and he loves that game. I use the MPG gauge on my truck, but it's always a question on how far I let it sink while accelerating. It goes lower for a shorter time with moderate acceleration, is that better than higher for longer? I can't do that math on the fly.
I think driving a car with a limited electric range automatically makes people more aware of energy usage. I wonder is LeMans cars have that? I know they can monitor it and use different maps to change how they use power/fuel, but is any of the figuring done by the driver or is it all in the pits? I wonder if there would be a benefit in crapcan racing to being able to monitor energy useage/lap times to maximize pit strategy? I'm sure there is, I just don't know how to do it.
mazdeuce - Seth said:I think driving a car with a limited electric range automatically makes people more aware of energy usage. I wonder is LeMans cars have that? I know they can monitor it and use different maps to change how they use power/fuel, but is any of the figuring done by the driver or is it all in the pits? I wonder if there would be a benefit in crapcan racing to being able to monitor energy useage/lap times to maximize pit strategy? I'm sure there is, I just don't know how to do it.
In my experience most changes related to the engine are coached from the pits.
Some cars have BSFC characteristics such that keeping the rev's a little lower will save enough fuel to give up a second/lap. This kind of thing is part of a pre-race strategy, and the driver is coached on it over the radio.
mazdeuce - Seth said:I have a friend with a Fusion Hybrid and he loves that game. I use the MPG gauge on my truck, but it's always a question on how far I let it sink while accelerating. It goes lower for a shorter time with moderate acceleration, is that better than higher for longer? I can't do that math on the fly.
IIRC, BMW did some studies a few years back that show that short periods of hard acceleration at low RPM is the way to go. Fewer pumping losses.
LeMans cars have interlinking limitations, such as average fuel flow over three laps and that kind of thing. I'll be the race engineer is advising the driver. I think a big reason we saw a shakeup in F1 when the hybrids were introduced is because some drivers are much better at assimilating all the various parameters than others, though - choosing when to deploy the limited battery capacity and adjusting driving style to prioritize economy over power, etc. I've been lucky to have some pretty in-depth conversations with one of Hamilton's race engineers, and there's a whole lot going on that people don't appreciate. Even the rate at which you press the accelerator during the pre-start burnouts has an effect.
Endurance racing is a fun game of chess. The crew chief and engineering team should be advising the driver on the ideal lap time to either make up positions or conserve fuel. Doing the calculation on juggling lap times vs pit stop time is fundamental race strategy.
rslifkin said:In reply to Tyler H :
Yup. Every car has an ideal acceleration rate. Too slow and you run into the "burning half as much gas for 4 times as long" problem of getting up to speed. Too fast and you're getting into power enrichment and high RPM and losing efficiency.
To really know that, you need the BSFC map. Something that might helps- if you can know when the car goes into enrichment for whatever reason, don't put that much throttle in. Then one also needs to have an idea of the high load/low speed knock vs. the higher speed/lower load pumping. Many times, engines are knock limited at low engine speeds and high loads.
Then again, knowing HOW you accelerate is also important- like doing a high load acceleration from a light is very different from a high load acceleration in top gear- one you are through the event quickly, the other may cause you to be in a trouble spot for a long time.
BTW, for those of you who have data loggers, you can take enough data via the port to get a good idea how the car runs- and do some rough calculations to efficiency. Then you can put this map together, and figure out how you should adjust your driving.
In reply to alfadriver :
Yeah, having some data (at least a wideband and instant MPG meter) makes it much easier to find that balance. And sometimes it leads to interesting results. In my Jeep for example, just about anywhere in the 40 - 60 mph range, accelerating in 4th and getting into fuel enrichment burns about the same amount of fuel as an equivalent acceleration rate in 3rd (which stays out of fuel enrichment due to higher rpm / lower manifold pressure).
alfadriver said:BTW, for those of you who have data loggers, you can take enough data via the port to get a good idea how the car runs- and do some rough calculations to efficiency. Then you can put this map together, and figure out how you should adjust your driving.
At least one of my datalogging apps has a "green" display. The lower your fuel useage, the happier the little plant on the screen is.
I have made the claim in the past that high cornering speeds are the secret to efficient driving, as they allow you to maintain momentum. Makes perfect sense but it's remarkably difficult to convince some people.
In reply to Keith Tanner :
If you take enough data- you can also get a graphical look at the BSFC map, not just someone's judgment on what is good or bad. It uses the same inputs at the "green" display does.
Bob the REAL oil guy. said:the old Alpha in the Rio got 34mpg always. hard on the gas, light on the gas... it didn't care. These newer engines don't like a lot of throttle.
My Honda is like this, I drive trying to get poor mpg, it does 30. I hypermile, it does 30. I confuse.
rslifkin said:In most cars, general driving style (especially how / when you coast and brake) matters far more for mpg than how fast you accelerate.
Yep I can beat my mom's MPG on her dash computer easily while accelerating harder and going faster. Shes driving within her vision and coordination lvl which means more braking.
If anyone (Alfa) has a moment to make up a rough plan for this ^ I would love to hear it.
I’ve been doing a little experimenting lately with the speed3 trying to see which is better: high rpm and high vacuum or lower rpm but lower vacuum. I know the car runs pig rich once it’s in boost but below atmospheric it’s hard to tell what’s going on. With a bike on the roof at freeway speeds I pick up 2-4 in-hg by running in 5th instead of 6th. 6th puts me at atmospheric when I’m going up anything resembling a hill. I know it’s much more complicated than that but it’s interesting to watch.
Pete Gossett said:In reply to Bob the REAL oil guy. :
She must drive like my wife.
And mine, but add a 300HP V8.
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