i am looking at buying a new car and the small hatchbacks appeal to me and seem to get good gas mileage. but sedans LOOK more aerodynamic. are they? is a hatchback usu. lighter? Does a lower weight minimize the “drag” that one would assume would decrease the gas mileage relative to a sedan? (isn’t the back of a hatchback similar in aerodynamics to the flat back of a truck?)
All vehicles are designed to take advantage of aerodynamics. Some work better than others, but you can’t assume anything just by looking at a vehicle.
You also can’t assume a hatchback is lighter than a sedan. The Hyundai Accent hatchback weighs more than the Accent Sedan. Who knows why?
Check the mileage ratings for cars you are looking at. Personally, I’d accept a bit more aerodynamic drag for the utility of a hatchback or station wagon.
Remember, there are MANY things that contribute to the fuel mileage, or lack thereof, for any given vehicle. Shape is just one.
Don’t worry about drag, it’s one of the factors that show up in the EPA numbers. And a car having a flat back end is not nearly the problem as having a flat front end. In the '30s a German designer by the name of Kamm discovered that there was minimal drag problems from lopping off the rear end of of a vehicle (avoiding the need to have a ‘teardrop’ shape), hence the “Kammback” design. Read more here: http://en.wikipedia.org/wiki/Kammback
thanks, both of you. from wikipedia it sounds like drag is a factor (theoretically), but it takes a LOT less tapering than i thought to minimize it.
Pressure drag from the cross sectional area of the front of the vehicle (as well as speed) will have a greater impact than aerodynamic drag. Though, as it was mentioned earlier, a slippery front end causes less overall aerodynamic drag even with the low pressure drag behind a flat rear-end of a hatchback. I have a Mazda 3 hatchback, and the only thing you’ll notice is that the rear end tends to get dirtier than the rest of the car, a small price to pay for the utility.
What about some results?
Find a hatchback you like and compare the EPA mileage to a similar sedan. EPA mileage is quite close to real mileage these days. While you will get somewhat different mileage based on your specific use, the comparison between cars will be valid.
The hatchback design makes for a much more practical vehicle than a traditional sedan with a trunk. If carrying capacity and versatility are important to you go for a hatchback. The hatchback designs are virtually identical to the traditional sedan shape as far as aerodynamics and fuel efficiency.
The car’s door configuration (hatchback/sedan/coupe) has no bearing on its uel efficiency. There are aerodynamic, fuel efficient hatchbacks and there are hatchback SUVs. There are also little boxy hatchbacks. And there are probably even hatchbacks with big, fast engines (although I can’t think of one offhand).
Like others have said, don’t use that as a determination of fuel efficiency. Get a Consumer Reports New Car Buyers’ Guide at the local bookstore and test drive what looks good to you. That’ll give you EPA estimates as well as lots of other data.
maybe not a big engine, but the MazdaSpeed 3 is pretty fast. The engine that the CX-7 uses, 2.3L turbo charged 4cyl(263hp @ 5.5k rpms and 280tq @ 3000 rpms) actually comes from the Speed 3 hatchback. 0-60 in about 6 seconds