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You have reached many of the same conclusions I have. I just can't come up anything that's not ugly. When you mentioned your plans for a Kamm-back, I wondered if you'd reviewed the videos, as they show much more of the dynamics than stills can. What struck me most was the outboard edges of the rear glass, where the airflow on the glass is substantially perpendicular to the high velocity flow coming off the side. It's a classic example of how to truncate the back end for a clean break, unlike the quarter panels below it. Things like this are one reason I did the tuft test; a Kamm-back was on my radar, too, but I think Ford beat us to it. As to those wonderfully generic and aerodynamically horrible quarter panel curves you see on so many recent designs... the challenge is being subtle; Ecomodder's full of not-so-subtle examples. Subtlty is what got me interested in vortex generators as a way of using air to modify the air flow. The challenges of putting flat devices on curved sheet metal led me to try them on the rear roofline, with negative results confirming for me the discussion above. I'm now modifying the devices to fit the bodywork contours, and will re-test if I'm successful. At least on the quarter panels, there's not much you can do to make things worse... In fact, that's the second challenge to a VG approach; VGs work best when fed laminar air flow, so placement matters. They aren't as effective when placed in turbulent airflow, like that seen from wheel well level down on the rear quarter. The air never reattaches after being separated over the wheel well. The obvious solution is wheel skirts, or at very least, mini-skirts. Looked into variations of the Gurney Lip, placed parallel the air flow to segregate turbulent air from laminar regions. Most wheel turbulence comes off the top (it's going 2x car speed), so even a small skirt should extend laminar flow farther down and back. You'd need a full skirt to get smooth below bumper level. So, I'm looking at VGs on the upper half of the quarter panel, starting in front of the tail light and going down to wheel well level. It's only half the available real estate, but it's the only laminar region. We'll see if I even get them on... Have fun, Frank PS example of Volt rear quarters from Ecomodder's car modification FAQ. Click the video link (to an Ecomodder thread) and scroll down to aerohead's comments. He was the source for post #9. Insightful comments.

Your understanding is correct if you look at a wide enough range of tire pressures, extremely wide, like 10-100psi. In the pressure range we're discussing, 30-50 psi, greater pressure results in better handling and more stick. Keep in mind that we're talking about tendencies and gradients - which way things go if you change something. We're not talking about large changes in performance, certainly not one that any sane driver would notice. These changes are only obvious at the cornering limit, when the car is trying to rip the tire off the wheel. I raced for years, and the easiest, fastest way to optimize handling is by adjusting tire pressures based on tire performance, regardless what the sidewall says... But we're not racing, we're using hybrids for mileage, and for fuel consumptioni, there's no downside to higher pressures. Conversely, a little common sense is always appropriate; I strive for the informed decision - set them where you are happy!! HAve fun, Frank

I assume you added emphasis to make a point. You see a link between tread compound and tire carcass and bead construction? Please explain... Frank

Welcome! I have found this among the most adjustable cars for driving position. Have you used all the range of motion from the seat? It took me a while to find height, and I didn't like it all the way up, even with plenty of headroom. It seemed there was a sweet spot for my head... How about the steering wheel? There's a lever on the bottom side that lets you do just about anything by way of in-out or up-down. The idea is to adjust the seat so you're getting ventilation, visibility, and can reach the pedals, then move the steering cluster so you can see the instruments and comfortably steer. As others have noted, memory seats would be a real plus for those of us who share driving duties. HAve fun, Frank

I'll trade a little cold and snow for mudslides, wildfires and earthquakes any day... no one gets off scott free! And we had a new record low for the day yesterday! Frank

I like to run mine at minimum, and no, it doesn't reset on it's own. It reset when I got 13B07 PCM update (no surprise) and I noticed right away (also no surprise; some things matter). Have fun, Frank, who's wondering if we're about to convert another Prius driver...

??? I'm seeing $716 at tire rack for OEM Michelins (there are two 225/50-17 Energy Saver tires; the OEM's the one with the 51psi pressure rating). Keep in mind you only started with 9.5/32, so even with a 3/32 "worn out" criteria, you've used about half the tread, and seen less than half the life as tire wear rates drop as the tread gets shallower. It's one of those wonderful tradeoff triads: longevity, traction, rolling resistance - pick 2. Michelin has traded off traction (see Car and Driver review, Tire Rack test report wet braking) for rolling resistance and life by using a harder rubber compound in a shallower tread, resulting in a light weight tire that wears well, but doesn't stick. Have fun, Frank, who's fine not having it all.

Yoko Avid Ascend tires are a good product (killed several sets), but I have no expectation they're in the same league as the OEM Energy Savers for rolling resistance. There's very little on the spec sheet that actually affects rolling resistance; a "green," "blu" or other LRR designation tells you what marketing message the vendor wants you to hear. Tread depth is the exception; reduced rolling resistance tires will have less tread depth than a normal tire. Micheln Energy Saver: 9.5/32" Yoko dB Super E-Spec: 10/32" Yoko AVID Ascend: 12/32" I expect the 12/32" tire will have higher rolling resistance than the others when new. It will also either last longer or have more traction, or both, but at the cost of rolling resistance... HAve fun, Frank

Check ETIS, selecting "minor features" at the lower right. You should get a list of all features, telling if you have them (with) or you don't (less). For example, my car has the pano roof, but doesn't have a spare tyre, immersion heater or remote start. Frank Minor Features Medium Light Stone InteriorWith Roof Conversion-Panorama RoofACC Media Hub 2XUSB+AV+SD SlotWith Power Liftgate ...With Automatic Windscreen WiperWith Front Licence Plate BracketBelt D & P Fr 1 & 2 Row/D Kne BagTether Anchorage Restraint-Style 217" Alloy Wheel Style 2Less Spare TyreLess Immersion HeaterLess Remote Starter50 State Emission Requirements

+1 We have an SEL Hybrid with MFT and no remote start... Frank

It's a couple weeks later and I'm very happy with the results (so far). Ordered Ice Storm in spray can, with laquer, cutting cream and degreaser (naptha). I got the color coats on last weekend, hoping for the clear coat this weekend (got windy Sunday). At this point, you can't see a color difference as long as you can't see any specular reflections. Look at the shine and it's obvious where I've yet to apply the clear coat. I like the color match I'm seeing, and expect the rather large touch-up will be nearly invisible when I'm done. A good result from paintscratch.com. Frank

Thanks!

There are two approaches, change how you're driving, and modify the car. The latter is to simply block off the front grill, improving aero drag and reducing the amount of cold air to the radiator and engine compartment. Look for work by Recumpence and ptjones, confirming engine temp is OK, and mileage rises. Others have hit on the driving changes to some extent. As I just noted to someone else, there are several stages to warmup. Stage 1: cold - ICE on continuously, turns off when warm, not hot Stage 2: warming warming 1 - EV only available with heat OFF warming 1a - ICE will come back on and stay on warming 2 - EV limited to 1 bar with heat ON Stage 3: hot- full EV available and ICE turns on/off with throttle I drive uphill for most of my first mile in the morning. I run defrost max until I hit the main road; turn heat off and I can EV. I take this as far as I can, and get a long second warmup run as a result. After the second ICE warmup run, I can EV with the heat ON, but only use 1 bar, perfect for a long flat run. From here, I play with heat and throttle but retain the 1-bar limit until I'm a good 5-10 miles from home... And that's on a 25F day. Haven't had any lower, yet... Have fun, Frank

Nice look!

Please forgive Jus... he's been C-Max-less for about a month now and I think hallucinations have started...

Yes, I need to write up what became tire pressures AND upper grill seals. Mileage improvement was modest, +1-2%, and temperature dependent; 1% at 60F, 2% at 40F. I expect most of the difference is tire pressure, especially the slope change, but the upper grill block is invisible and the hood seals are the right thing to do, so it all stays. I'm curious to see a repeat of the grill cover testing, post 13B07 PCM update. I didn't treat the lower grills so I didn't interfere with stock cooling, knowing the PCM update included changes to louvre operation. I am curious is the large benefit initially seen with grill covers has dissappeared. That would get at the aero contribution vs. warm-up for front end treatment. And my pizza pans have been the source of spousal entertainment as well... we'll see when they're on the car. HAve fun, Frank

The headlight upgrade game was far more fun back in the seal beam days... It's not the extra money for higher wattage bulb that bothers me, it's the burned out ground terminal on the connector. Of course, those were 100W bulbs... IMHO, you're upgrading even if they're not brighter. I know of no rational reason for bluing on a headlamp; high color temperatures have huge disadvantages because blue light scatters. In fog or snow, you see a wall of white, not the road. I've driven many a snow-covered interstate, and the issue isn't traction, it's visibility - seeing the edges of the road through the glare of headlights reflecting in the airborne snow. There's a reason fog lights are yellow (and I drive wearing blu-blockers when it rains). HAve fun, Frank

That's a very pretty car you have there! How about some details; what did you use, where'd you get it, etc.? Have fun, Frank

This is a great car that's great on gas, too. Treat it like a sports car and you'll get sports car mileage. Treat it like a hybrid and you'll get somehwere between 35 and 60 MPG, but be prepared; the pattern of high and low is backwards! I realize that's a heck of a mileage range, but speed matters. Doing 70MPH, I'm getting about 38MPG if I exclude acceleration, on-ramps, etc. Driving back roads to work, 55MPG for the round trip is going to come up regularly... but I'm only averaging 30 mph. And that's just the beginning... HAve fun, Frank

I mounted them even with the front edge of the hatch lid, including the curvature as the tuft test showed that airflow isn't parallel the the direction of motion, it's slightly skewed there. If you recall that I reported the hatch was recessed downward a little? I was aiming for the tab's mouth to be flush with the roof when mounted on the hatch. I was going to take pics but didn't; another sign of subliminal bias??? Have fun, Frank

Thanks for the offer Jus, but Marj is best described as "tolerant" regarding my science project, because when she isn't, I remind her who named it a "science project." Paul you and Matt have me wondering if my pizza pans are going to stay on! (They're wheel covers for snow tires.) I replied on the aero mod thread.

I know I've posted this graphic already, but I've no idea where... This is from a Masters' thesis looking at brake rotor cooling.The hypothesis is that the larger open area on the wheel, the more cooling you get, and the data seems to support that trend, up to a point. The open alloy wheel has far better brake cooling than the others, and comes in second when blocked (spokes act as vanes?). By way of calibration, I measured C-Max wheels and they have ~360 sq. cm of open area. The Ford steel wheels I'll use have about 100 sq cm open area. I expect you'll see a much higher pressure behind an alloy wheel cover than if you were covering a steel wheel. By way of confirmation, can you tape over the alloy wheel spokes? That would eliminate air pressure from under the car; maybe something else is going on? HAve fun, Frank, who's now wondering if belt and suspenders will be sufficient...

First off, I didn't test GasPods, but rather AirTabs. My intent was exactly as you describe; install them in a vertical line from behind the taillight down behind the wheel well. As the link details, bodywork curvature proved insurmountable; I need to modify the AirTabs so I can mount them on the car's contours. Instead I tried the roofline, with negative results as discussed. I would be interested in anyone's results who has put GasPods on the sides... or who has other ideas for addressing the flow separation, beyond new bodywork. Anyone could slap on a Prius-tail! HAve fun, Frank

Many of us have had a similar problem related to the "Easy Fuel" capless system not closing properly, resulting in a "check engine" light while driving. The "check fuel filler" message is new to me, but I've poked the funnel into the filler cap a couple times now to turn the light out. Only filled up 7 times, had 3 lights... The danger is that something big could be wrong, so you don't want to live with a Check Engine light, and never, ever ignore a flashing Check Engine light. If your mileage is taking a dive along with the thermometer, put air in your tires. The cold weather has you underinflated, I'd wager; I was. I will recommend setting them to the sidewall rating, not the placard rating, for lower rolling resistance, and less temperature sensitivity. The other thing you can do is turn off the heat whenever you'd like to EV. Assuming you're a recent build, your C-Max has a 2-stage warm-up, they say, but I see 4 stages. 1) engine cold - ICE always runs until warm 2) engine warm but not hot - EV only if the heat's off, and an extended run the second time ICE turns on 3) engine not hot enough - EV limited to 1 bar when heat is on, but ICE turns on/off as normal 4) engine hot enough - full EV capability with heat on. This seems odd, but I've confirmed the EV limitations several times. Have fun, Frank

You've described my in-head discussions to a T. My mind likes to visualize, so I've been trying to see the airflows above the surface as well as on it. There's enough out there on VG's that their basic function is not hard to understand. It's the interaction with other solids in the air flow; VGs on wings that serve to increase lift and/or prevent stalls... That's one reason I tried AirTabs; I can see how a panel edge can be extended aerodynamically by an array of vortices comming off the edge. My thought process was to add them down the side, from taillight down. The vortices would form parallel to the ground and create a barrier to air wrapping around the side, not unlike a boattail. We'll see if a little sanding and heat re-forming can give me parts to test... in the Spring. BTW, my subjective impression of my AirTab test was also negative; I didn't "feel the glide." Finally, there was one test I didn't get to this weekend. I've got a pair of vacuum gauges and 40' of tubing, but didn't have the time to shake out the system and take useful data. When air is flowing over the car, it causes local pressure changes. As we alter the air flow on the car, we ought to see measurable changes in local air pressure, if your gauge is sensitive enough... Did I mention Sunday was my wife's birthday? Have fun, Frank