Just wondering


#1

I followed a prius up the road today He was driving real slow(maybe it was due to the overnight snowfall or maybe hyper mileing)I know aside from the regenerative brakeing,a lot of the great mileage comes from design.My question is how come the manus dont incorparate more of the gas saving features in their other non hybrid vehicles? Doesnt seem like aerodynamics and low rolling resistance tires,start stop on the engine,etc, would cost that much to incorparate on a standard compact(even the pickups would benefit)-Kevin


#2

Going too far with the aerodynamics could lead to unappealing styling and functional compromises (like mirrors that are on the small side). LRR tires often give up other desirable characteristics. Not everyone wants to make these tradeoffs.


#3

Some do. BMW uses start/stop for some cars in the USA.


#4

Yep, several of the features are being incorporated. But the major features that make a hybrid save major gas pretty much require the hybrid battery and electric motor.

GM tried going the ‘mild hybrid’ route on several vehicles, but folks didn’t want to pay for the features given the limited improvement they saw.


#5

Our 09 Chev Cobalt XFE is set up somewhat as you mention. It has low rolling resistance tires that had poor winter and poor wet road traction when new but are a little better now with some wear. It has a higher final drive gear ratio than a regular Cobalt. The cruise control is not aggressive about matching the set speed when applied but is ok with maintaining the set speed. Supposedly the engine control has been tweaked to optimize fuel mileage. It has a manual transmission. The radiator cooling openings in the front end are barely large enough as noticed a few winters ago. We were on a trip and the cooling openings became partially iced closed in a storm resulting in overheating. I had to stop to break the ice away. It’s easy to guess that the minimal opening area is for better aerodynamics.

The highway EPA number is 37 mpg and with non-alcohol gasoline we can exceed that if we want. One summer evening just for fun I zeroed the average gas mileage calculator after we started out and was able to keep the average mileage at 50 mpg by driving at around 35 mph on mostly deserted paved rural roads with minimal stops and starts. Believe it or Not!


#6

Actually, manufacturers incorporate countless fuel saving technologies in their other vehicles. Including aerodynamics. Some of those technologies, like using ball bearings at the wheels instead of roller bearings because ball bearings have less rolling resistance, are tradeoffs. In the case of the bearings, they’ve traded off robustness (against potholes, for example) and longevity for a wee bit better mileage.

Manufacturers also must incorporate countless safety systems and technologies that prohibit some fuel saving ideas like rear view cameras (mirrors are mandatory). Crash protection, 5mph bumpers, and in Europe even protection for a passenger should you hit one, all limit many fuel saving technologies. You’ll find that the hood on your new car is heavy, because it’s designed to transfer and absorb inertial energy on impact. Were that not required, they’d probably be lightweight aluminum. Of course, more people might die in crashes if that were the case. Can’t have it both ways.


#7

RE: Aerodynamics, I think aerodynamics are being built into cars on a regular basis, that is why I cannot tell one brand from another from a distance.


#8

A manual transmission Honda Fit shuts down fuel to the injectors while in gear and feet off the gas. Rolling in neutral shows less mpg than rolling in gear.


#9

They often do, but don’t call attention to it as much. And there have been extra-efficient versions of various models available. I believe from Honda they were labelled “HX”. The problem until recently was that low-rolling-resistance tires were made in small quantities at higher prices. Adding bits like active radiator louvers and a bit of underbody cladding also cost, but even with all those features these cars never gained more than 2-3 mpg from them. They gained a bit more from changing the engine’s valve timing to be more like a hybrid’s, but that cuts power very noticeably.

People proved resistant to paying a significant premium for a slower car that gained little in efficiency. Many of the sales of these cars seem to have been to fleets (along with the LNG variants.) A hybrid can more effectively take advantage of some of the same technologies.

Engines that can operate in very different modes depending on power needs will become very common, with some gasoline enginrs even acting in a compression ignition mode (that’s where Mazda is going.) Then you’ll see some very attractive gains in mpg.


#10

I personally hate the start-stop feature a lot of new cars have. Although it may save a little gas, and cars are supposedly engineered so the constant stopping and starting the engine doesn’t affect longevity, to me it’s as annoying as that person that turns off the lights in a room when they are only going to be out of the room for a minute–like going to the fridge for a snack.

To add to that, some manufacturers are redesigning HVAC systems so you can at least stay somewhat cool when the engine shuts off at every stop. Again, in my opinion if you have to work that hard to save a minuscule amount of gas (CAFE regulations be damned), you’re working too hard and have reached the point of diminishing returns. There has to be a better way.


#11

@Wha Who,I believe you ,my question sort of revolves around the operating modes(seems people are largely ignorant of the real sweet spot of operating modes for a Hybrid) I’d say the Hybrids are probaly not that much better on the highway because there are several vehicles now that can hit 40 mpg on the hiway,these automatic Civics we own seem to average around 37 mpg with the AC on and no particular attempt at fuel saving,what I have noticed on the Prius is the careful attention to aero dynamics and so forth,I believe a non Hybrid Prius would do good on the hiway(Kinda like the argument for and against ABS{abs’s primary function is to maintain straight line control and steering control of the vehicle} most Folks dont seem to understand that-kevin


#12

The problem is we’re talking about two different classes of vehicles: economy compact cars and hybrids. People want one or the other, not a combination of the two.

What you’re talking about - integrating some fuel saving features into non-hybrid cars - is what some manufacturers have been doing for a long time. In the 1990s Honda sold a Honda Civic HX, which came with a special engine tuned to run leaner than the other Civic models and a CVT transmission. I guess the Civic HX wasn’t popular enough to continue making and selling them, or perhaps Honda incorporated the fuel saving features of the Civic HX into future generations of all of its Civic models. I kind of wish I had considered the HX when I bought my Civic, but I wanted a stick shift, not a CVT, and I wanted a model that would last a long time, not something that had been experimentally modified.


#13

The most aerodynamic of the post war cars of the late 1940s was the Nash Airflyte. These cars had about half the co-efficient of drag than its nearest competitor. The 600 model was powered by an engine of about 172 cubic inches. The car was a truly a 6 passenger family car and the 600 designation came the fact that it could travel 600 miles on a 20 gallon tank of gas. However, there were disadvantages to the design:
\1. Both the front and rear wheels were fully enclosed–no cutouts. This increased the turning radius and made it difficult to change tires. Fully enclosing the wheels did make the car more aerodynamic.
2. The aerodynamic shape limited visibility to the rear. The rear window was more like a sky light.
3. Many people thought the Nash Airflyte design was ugly. This did hurt the resale value of these cars. (I found them quite attractive when I was a kid);


#14

The manufacturers are adding many of the tricks from hybrid models such as Stop-start,active aero (grill shutters) and low rolling resistance tires. Which is why you can buy a gas engine compact that gets 40mpg on the highway where previously most were rated for mid 30’s at best.Hybrid’s like the prius can do even better on the highway (55-60mpg highway in mom’s '10 Prius,closer to 50 in town)


#15

If you really need the economy benefits of auto stop, but your car lacks it, well…

All this newfangled effeciency stuff–auto stop, fuel cutoff while coasting, grille blocks–is stuff hypermilers have been doing for many decades (HM goes back at least as far as WWII fuel rationing). The big change is that new cars hypermile as a “default setting”…just makes it less of a PITA, and increases participation rate.


#16

The Prius engine also uses an intake cycle that keeps the intake valves open briefly after the compression stroke starts. This maximizes efficiency, but at a cost in total power. The hybrid system makes up for this reduced power at lower speeds, and at cruising speeds you don’t usually need anywhere near the engine’s maximum power. So a Prius can get better highway mileage than most cars of similar size (and is rated for it by the EPA, for what that’s worth.) During our carless years we drove them extensively (from ZipCar), on long trips and short, and never gotten less than 45 mpg, driving conservatively but not hypermiling. On one tank we broke 55 mpg, but that was mostly driving down CA Hwy 1 at a steady 50 MPH with the AC off.

The only time the Prius really struggles is when it needs maximum power at speed, such as climbing a grade heavily loaded, getting up a steep, short onramp, or passing. Otherwise, it’s not exactly a quick car, but that’s only in comparison to the power even economy cars now offer. 20 years ago the Prius would have been an average performer.


#17

Thanks for the replies ,still not sold on CVTs-Kevin


#18
Thanks for the replies ,still not sold on CVTs-Kevin

While researching my new car purchase I choose the Highlander over the Pathfinder because the Pathfinder had a CVT transmission. I know this guy who owns a transmission shop in NH and he’s seen a lot of CVT transmissions in for rebuilds. Say’s they’ve improved over the years…but there are still some problems. And they are EXPENSIVE to repair.


#19

The Prius ‘CVT’ is really a misnomer. It works nothing like other CVTs with their belts or friction disks. Instead, all it has is a simple planetary gearset, just like a differential, with engine output (and power from the enlarged starter motor/generator feeding one input, another electric motor/generator connected to another input, and finally an output shaft, which also feeds power back to the motor/generator for regenerative braking. Sometimes just the motors are driving the car, other times the engine and one motor are, with the other motor running in reverse as a generator. That’s why it’s described as a cvt. The second motor can be run forward or backwards, changing the gear ratio between the engine and the output shaft. The smaller motor is connected to the engine and is there mainly to get the engine started and allow a smooth handoff from pure electric propulsion to engine+electric. It also adds a little extra power to the total when needed.

I really wish Toyota had decided to call this something other than a cvt. It does have somewhat the same effect, but achieves it through radically different means. The basic concept is not at all new, btw, though Toyota has patents on a number of important refinements. Ford developed their very similar technology separately before realizing Toyota had applied for patents on some critical bits. That’s when Ford licensed the technology and can call it Hybrid Synergy Drive, like Toyota. Nissan also bought in.

Most Honda and Hyundai hybrids use much simpler arrangements with the electric motor beteeen engine and conventional transmission, with or without a clutch, and without the planetary gearset. This makes packaging easier, but requires some kind of conventional transmission and so far hasn’t given competitive gas mileage. It’s also not been as robust. Priuses are quite reliable, especially the previous generation. The current one is more average, but not due to drivetrain problems.

One of the German companies is going to connect the motor to the other end of the engine’s driveshaft (I think a clutch is involved. This scheme is simple, but barring more gearing or a more expensive engine design, it looks like the engine will only be contr-ibuting at lower speeds. Which is OK, as that’s where the biggest gains are to be had. It’s likely to be a city car primarily, so highway mileage is very much a secondary concern. For that, they’ll sell you a very efficient diesel.


#20

Based on what I’ve been reading about in the hypercar world, much of which often trickles down to real-world cars, I’d expect in the not-too-distant future we’ll be seeing systems that use electric motors not as a primary power source at low speeds but rather to get acceptable performance from much smaller gas engines, which will be the primary power source at low speeds.

Speaking of reading, I’ve also found that the European car magazines get much deeper into the exploration of these new technology applications than the U.S. based magazines, and do so far earlier. Perhaps it’s because most of the hypercars are made and sold in European countrys and are made available to the press there first. When was the last time Ferrari, Lamborghini, Pagani, Rolls, Bentley, or the others that are “pushing the envelope” have made press cars available to the U.S. based press?