GTP Cool Wall: 2007+ Mazda2 hatchback

[homeforsummer]

Amongst regular production cars, 0.26 is smashingly good.

0.25 for mine

The Mercedes CLA is unbelievable though. 0.23 in regular production form. It makes you wonder how necessary the "Prius shape" is when someone can put out a fairly regular sedan with such a low Cd. Both Mercedes and Mazda are doing pretty well with regular shapes at the moment. Even the Peugeot 508 I've just had on test is the same as my Insight (though the Insight has a much smaller frontal area).

As for the next Mazda 2, there's a pretty fair chance it'll look pretty much like the Hazumi. All of Mazda's other recent production cars have looked like their concepts, as @Famine points out.

 

[niky]

Mercedes had to pull every trick in the book, though, to make the CLA look "normal"...

Here's something:

Notice how blobbishly the roofline, hood and trunk float over the top of the car. The nose is rather square-ish, and long, yes, but the rear is what's important for the aero-template. It approaches the ideal set by the Prius, as seen in the blueprints, but in real life, the styling covers it up:

Some angles don't flatter it, though.

Still love the looks of the car. Aching to drive one. And the shape optimization doesn't fully explain the ultra-low CD... it's apparent they spent countless hours tweaking the aero, likely finding a lot of gains in small areas that most people overlook.

 

[Grayfox]

The EV1 was hardly a regular production car. More like a lease-able lab experiment. Most cars in the 90's hovered around the low 30's, with very few dipping under.

Amongst regular production cars, 0.26 is smashingly good.

I know the EV-1 was a test car hence why I just said on the road, but 0.19 was very good and sad that a companies these days can't get that low for new eco cars.

 

[JAHHAJ]

It's meh.

 

[homeforsummer]

I know the EV-1 was a test car hence why I just said on the road, but 0.19 was very good and sad that a companies these days can't get that low for new eco cars.

The trouble is that few would buy such a thing because to get that low demands a completely different take on the car's shape.

The EV1 had a Cd of 0.195. The VW XL1 going on sale soon is 0.189 - but like the EV1 its shape is an acquired taste (I love it, but can see why some don't).

As car design evolves we may see more aero-efficient cars coming through, but for the time being cars like the Merc CLA are likely to be the most aerodynamic we get. Frankly, the CLA is hugely impressive for what it is. The Tesla Model S is 0.24 which is also fairly slippery, but then the Model S is enormous so its CdA will be higher than many. Automotive aero is a hard game to win since it's always a trade-off between drag, styling, and being able to squeeze a certain number of people and things into the car.

 

[Grayfox]

The trouble is that few would buy such a thing because to get that low demands a completely different take on the car's shape.

The EV1 had a Cd of 0.195. The VW XL1 going on sale soon is 0.189 - but like the EV1 its shape is an acquired taste (I love it, but can see why some don't).

As car design evolves we may see more aero-efficient cars coming through, but for the time being cars like the Merc CLA are likely to be the most aerodynamic we get. Frankly, the CLA is hugely impressive for what it is. The Tesla Model S is 0.24 which is also fairly slippery, but then the Model S is enormous so its CdA will be higher than many. Automotive aero is a hard game to win since it's always a trade-off between drag, styling, and being able to squeeze a certain number of people and things into the car.

But with todays cars engine that can get 80MPG(UK) with diesels that can hit 100mpg or even more.
The VW XL1 is a proof of concept car.

 

[homeforsummer]

I'm not sure what your point is. I've explained why dramatic aerodynamic changes are difficult to make happen. The type of engine used isn't hugely relevant in that respect.

Let's say you want to get a car like the next Mazda2 to do 100 mpg. You are limited in how you can hit that target because the Mazda 2 is a fairly small car and you need to find space for an engine, four to five passengers, and some luggage.

There are only so many things you can do the the body of that car with those constraints in mind. You could give it a Prius-style roofline, but then your rear passengers wouldn't have much space for their heads. You could make it larger to counteract this, but then you've built a car the size of the Mazda3 instead. You could pull every cheap aero trick in the book like a raked windscreen, rear wheel covers and a kamm tail, but then you've made the car look odd and nobody will buy it.

The least I can see a regular B-segment hatchback getting down to on Cd is maybe 0.25 or 0.26 in the next decade or so, and that's after plenty of work. The current best in class is probably the Mitsubishi Mirage at 0.27, but that's hardly an appealing shape.

The best way of getting something like a Mazda2 to 100 mpg is probably clever engine technology. Diesel is a good start, Skyactiv diesel is a better one. Throw in Mazda's i-ELOOP energy capture system for running all accessories, chuck in an engine-off coasting function like Volvo announced in Geneva for a new variant of its V40 and maybe even throw a small electric motor in there like Honda's old IMA system, and 100 mpg would be in reach. Though you then have quite an expensive small car...

 

[Grayfox]

I would just love to see more eco cars every day.

 

[Famine]

Chuck in the fact they're rated at 76mpg for the SkyD Mazda 3 too. I recall the Japanese market gets a hybrid...

Getting a super low Cd is easy if you don't mind making a small two seat coupe with colossal overhangs. When you add in requirements like taking four passengers or any luggage at all, fitting into regular parking spaces or actually driving places it becomes trickier. By the time you get to the point of packaging the car so your mechanics can actually get to the parts they'll need to replace and it's not a 4hr job to replace a blown headlight bulb, so many compromises have to be made that just hitting 0.30 is impressive. 0.26 is potty - 0.23 moreso, but then it's a Mercedes and their customers won't care about the stupidly long service times (or Mercedes won't care if they do)

 

[homeforsummer]

One thing I found unusual was that for a period in the 90s to early 2000s, automakers kind of gave up making their cars aerodynamic. Plenty of cars in the 80s and early 90s had drag coefficients around 0.30, a few less than that. Not to mention that cars in the 80s were a little smaller anyway - from an efficiency point of view, it's just a pity the engines were so crap. Then all of a sudden everything was in the mid 30s for a while, as seemingly everyone struggled to hit the twin targets of styling a car and making it aerodynamic.

Now, everyone seems to have got the knack again.

 

[Grayfox]

One thing I found unusual was that for a period in the 90s to early 2000s, automakers kind of gave up making their cars aerodynamic. Plenty of cars in the 80s and early 90s had drag coefficients around 0.30, a few less than that. Not to mention that cars in the 80s were a little smaller anyway - from an efficiency point of view, it's just a pity the engines were so crap. Then all of a sudden everything was in the mid 30s for a while, as seemingly everyone struggled to hit the twin targets of styling a car and making it aerodynamic.

Now, everyone seems to have got the knack again.

Not to mention they made cars wider and heavier.

 

[homeforsummer]

That too, though again that trend is reducing somewhat now. Will be interesting to see how much the next Mazda2 weighs, since the current one is already a decent chunk lighter than the Demio it replaced and indeed lighter than most other cars in that class too.

 

[Grayfox]

I miss the days of when a "small" car was "small" and not a medium car in a small cars clothing

 

[homeforsummer]

Those cars still exist. Every time a particular line of car grows to a certain size, a smaller car is squeezed in beneath it. 40 years ago the Golf was the entry-level VW. Then it was the Polo. Since then, it's been the Lupo/Fox/Up.

It's not a trend likely to continue much more anyway. Modern production cars are already more or less as big as they need to be in each segment anyway - the average B-segment car can typically hold four adults now provided they aren't all lanky freaks, so there's little more incentive for them to grow. Hell, some A-segment cars can now hold four people up to my sort of height (5'9" ish) with headroom and legroom to spare, so again there's little reason for those to grow.

Now that size is remaining relatively static it'll be interesting to see what happens with regards to weight. The gradual bloating over the last 20-30 years seems to have slowed now (though there are exceptions), and several cars have got significantly lighter in their most recent generation.

 

[niky]

Want a small car? The Mirage is just as light and as fuel efficient as a 90's Civic VX hatchback, while offering more space and more crash protection. Granted, it's nowhere near as much fun to drive as the VX, but it's an amazing feat, considering the Mirage can't use the ultra-lean burn technology that the Civic had (won't meet emissions regulations nowadays).