What makes cars fuel efficient?

[suprapsu]

Cars back in the day were much more fuel efficient than todays cars.

For example.

The 1992 - 1995 Civic VX gets from 42 - 60 MPG
The Geo Metro Xfi gets from 40 - 65 MPG

From my observations what makes these vehicles so fuel efficient?
1) Lower HP
2) Light Weight

Now comparing to Compact cars today why can't we have gas efficient cars like these without the battery pack?

I think safety regulations play a big deal in part of this because there are certain guidelines to how much a vehicle has to weigh and there is a min. HP it has to have.

Even the new Chevy Aveo gets 24-34 MPG which I think its not that great when you factor it's 1.6liter engine and it's weight of 2300lbs. It should be getting at least 30 city and 40 HWY

Is there anyway to modify the Aveo's transmission so that it gets this kind of MPG?

[GasSavers_RoadWarrior]

I also blame whiny barsteward auto hacks and reviewers who complain about 0-60 times being "poor" at 9 seconds.... back in the day anything doing better than 15 was a sports model. Least powerful motor you can buy in a compact these days? 105 HP I think... which was the most powerful motor you could get in a Chrysler minivan back in 1985...

[jbmorse02]

Originally Posted by RoadWarrior

I also blame whiny barsteward auto hacks and reviewers who complain about 0-60 times being "poor" at 9 seconds.... back in the day anything doing better than 15 was a sports model. 1985...

I agree. My dad's 83 vw westy weighs a lot and has something like 84 horsepower. The only time this is a slow vehicle is when you start out on a steep hill. It's adequately powered and maintains 70mph easily.

People think they want power but they don't realize you don't need much. In Europe small cars can come with 1.2 liter engines. In the US, if you want a vw rabbit, you get a 2.5l 5 cylinder. Isn't this overkill?

[GasSavers_Ryland]

horse power is always peek horse power and that peek is around 5,500 - 6,000 rpm on most civic engines, the peek torque on the other hand ranges between 3,000-4,500rpm, the cars that get better mileage tend to have better torque and at lower engine speeds like the crx hf had peek torque at around 2,500rpm and because of that feels like a very powerful car even tho the peek horse power was around 60hp.

[suprapsu]

i own a civic VX and I have to say its not that bad. I get good FE and not have to sacrifice performance. I also had the geo metro and I have to say that its handling was pretty bad but its performance was okay to get by with.

[kamesama980]

less efficient: more cams and valves. more moving parts, more friction parts (more valves=more pressure against cam, more resistance as they have to climb the lobes, more pressure on bearings). Emissions equipment and tuning, both noise and gaseous.

that's why the dinosaur of an engine in my truck gets 25 mpg mixed. 4 speed manual (no OD), 2.5l (big engine for this forum), and a computer that makes a pocket calculator feel good but OHV and a gear-driven cam. that and the springs are so light the valves float over 5k or so I've heard. hell it got 24 mpg going 65mph carrying 1000lbs

[1993CivicVX]

It's a conspiracy I tell you.

[Hateful]

Was just looking up my drag coefficient (.36) and saw lots of bad reviews saying my Cavalier didn't have enough cam and valve stuff and only 115HP.I didn't see any complaint about the high drag or low EPA estimated MPG's.

[dkjones96]

Originally Posted by Hateful

Was just looking up my drag coefficient (.36) and saw lots of bad reviews saying my Cavalier didn't have enough cam and valve stuff and only 115HP.I didn't see any complaint about the high drag or low EPA estimated MPG's.

OHV 2.2? Wonderful engine, doesn't rev well but down low it pulls great. Gotta say it's by far one of the best 4 bangers I've ever driven too. With the 36MPG freeway, a/c full blast and 80mph cruise speed I can't say I was unhappy with the mileage either. 219k miles and lost MAYBE 1/4th quart of oil between 5,000 mile changes. The only reason my 2.0 now even slightly holds its own against it is it's cammed to make peak torque at 3,000rpm and nothing past 4500 lol

As far as inefficiency, I'd say size is one factor but the engine is your biggest culprit. That 1.6 in the Aveo we actually ran some testing on yesterday, that poor little engine is so gutless down low I'm suprised it gets 24MPG driving around town as it is, probably the low displacement. It's the first car I've seen we had to redline to make it up a couple of the acceleration ramps on our fuel economy test. Engine inefficiencies is one of the things I hope to address when I start working R&D with an automaker (crossing fingers).

[VetteOwner]

Originally Posted by dkjones96

OHV 2.2? Wonderful engine, doesn't rev well but down low it pulls great. Gotta say it's by far one of the best 4 bangers I've ever driven too. With the 36MPG freeway, a/c full blast and 80mph cruise speed I can't say I was unhappy with the mileage either. 219k miles and lost MAYBE 1/4th quart of oil between 5,000 mile changes. The only reason my 2.0 now even slightly holds its own against it is it's cammed to make peak torque at 3,000rpm and nothing past 4500 lol

As far as inefficiency, I'd say size is one factor but the engine is your biggest culprit. That 1.6 in the Aveo we actually ran some testing on yesterday, that poor little engine is so gutless down low I'm suprised it gets 24MPG driving around town as it is, probably the low displacement. It's the first car I've seen we had to redline to make it up a couple of the acceleration ramps on our fuel economy test. Engine inefficiencies is one of the things I hope to address when I start working R&D with an automaker (crossing fingers).

lol exactly, i was hauling around about 400 lbs of dirt + me and another adult around in my 2.2L s-10 and acceleration was no different. sure its only got like 96 HP at the wheels but it has a buttload of torque

chevette engine specs1.6L all iron everything)

bore and stroke: 3.228 x 2.980
82.0 x 75.7 mm

compression ratio: 8.5:1

net HP/@rpm: 70 @ 5200

max torque@rpm: 82 @ 2400

i belive 0-60 was in the 17 second range