Fuel economy in new cars

Status
Not open for further replies.

dishdude

$100 Site Donor 2023
Joined
Nov 14, 2008
Messages
16,390
Location
Phoenix
I was driving last night thinking about a couple threads where people mentioned how good fuel economy was in some 80's and 90's econoboxes. I don't disagree, but as I was playing around with the instrument cluster in my Jeep, it hit me that this large SUV with a V6 that puts out 290 hp gets the same mileage as one of my first cars did - a beat up old K-car with a 2.2 that brand new put out a tire scorching 93 hp. By time I got it with a gazillion miles on it I am sure it was a lot less! Considering the weight, size and performance of this vehicle, is there ever a better time to be a car guy? This large vehicle gets 24 MPG without me even trying.

 
Yep Horsepower is the big diff.

My 96 Mustang can get 28/29 MPG doing 65mph in 5th gear.

BUT. It's a 3.8L making like 130 HP or something pathetic.

NOW a 4 cyl can make that and get 40mpg, or 300hp V6 could get the same.
 
I still remember and was impressed with the awesome fuel mileage of the neons and cavilers. They weren't straddled with emissions like the new ones, so It really is impressive they get gas mileage, less pollution and more HP.
 
Engineers are squeezing more horses with less displacement these days. And body weight of autos have gone down. And better transmissions allow engines to turn slower and gas mileage is better. Just got back from a 1500 mile trip in the wifes Camry. Mostly highway at about 80. Got 31.4 MPG per the car. Getting better but I still think they could get quite abit more mileage from them
 
Originally Posted By: dishdude
This large vehicle gets 24 MPG without me even trying.

What kind of driving?

Wife's q5 will get 24, but only in strictly hwy driving. Anything else, and it's in the teens, mid teens even.

It is pretty heavy though and permanent awd.
 
Originally Posted By: toneydoc
Engineers are squeezing more horses with less displacement these days. And body weight of autos have gone down. And better transmissions allow engines to turn slower and gas mileage is better. Just got back from a 1500 mile trip in the wifes Camry. Mostly highway at about 80. Got 31.4 MPG per the car. Getting better but I still think they could get quite abit more mileage from them


Weight is up significantly for all makes and models, mainly because of safety mandates and also because of increasing demands from consumers for features. The OP's new Grand Cherokee weighs about 1000 pounds more than a 1996 Grand Cherokee. Even the new F150 that dropped 700lbs going aluminum is still heavier than every equivalent F150 made in 2003.

The only car I've heard of dropping weight lately was the new Camaro, but only after going to a smaller platform, and only in comparison to the porky 5th gen.
 
Originally Posted By: Gasbuggy
You should run a few tanks on paper and see how accurate that gauge is.


Probably closer than most will admit to. The computer knows exactly how much fuel goes into the tank. Do you know how much gas you put in to make the tank "Full" and where that is each tank? Over time the 2 will get very very close to each other.
 
It truly is impressive. I know people say cars have gotten 30-40+ mpg for years, which is true. It isn't an equal comparison though. Look at the safety features that have improved, look at the size increases, look at the power increases, look at the capability increases that have occurred while simultaneously increasing fuel economy. I applaud the engineers.

If you look at muscle cars and crossovers I think you'll see what I'm talking about. I had an '07 Charger with the 3.5l V6. Truly a great daily driver, 250HP and returned 17mpg in the city and 24 on the highway. Now compare that to a '15 Charger SRT with the 6.4l V8 that boasts 485HP and still manages 15mpg city and 25 on the highway, it's an eye opener.

Now, the wife and I are looking to sell the truck and pick up a crossover. We've decided on a '16 Forester with the 2.5l H4. Here you have a vehicle which tops the safety ratings, has a phenomenal AWD system, and isn't completely anemic (I'll concede that 170hp is low by today's standards). Given all this, the car still manages to return 24mpg city and 32mpg highway. Impressive is all I can say.

Simply put, you get so much more out of today's vehicles than you do from a vehicle built even 10 years ago.
 
Last fall I bought a 2015 Volvo S60 T5 to replace my bride's 2012 Volvo S60 T5. The 2015 model gets about 10% better fuel economy with two fewer cylinders and about the same horsepower. Besides the smaller engine, the improved MPG comes from an 8-speed trans (vs 6-speed in the older S60) plus a system that automatically shuts off the engine when stopped with a foot on the brake, restarting when the brake is released.
 
Yep, weight and power have gone way up. MPG has stayed about the same.

My 3200 lb Focus with 250 hp gets better mileage than my old 2600 lb Mazda Protege with 125 hp.
 
aerodynamics,drivetrain, and tires..
it only takes 10-20hp to maintain most speeds.

if you actually use your 250hp engine to make 250hp you arent going to get 5mpg.
 
IIRC, 0.5lb of fuel per hp is common consumption? Been a long time since I read Hot Rod.

6lb/gallon, so 1/12 gallon per hour per hp. 60mph speed, 20mpg, means 3 gallons per hour. 36 horsepower required.

Very simplified analysis, ignores much.
 
My 2012 Buick Regal:
curb weight 3600 lb's, 6 speed trans, 2.0L engine, EPA rated 29mpg highway

My 2004 Malibu:
curb weight 3250 lb's, 4 speed trans, 3.5L engine, EPA rated 29mpg highway

I don't get it, bigger engine less gears and same mileage in the Malibu plus it is more pleasant to drive powertrain wise without the constant shifting and higher revving engine.
 
Originally Posted By: bradepb
My 2012 Buick Regal:
curb weight 3600 lb's, 6 speed trans, 2.0L engine, EPA rated 29mpg highway

My 2004 Malibu:
curb weight 3250 lb's, 4 speed trans, 3.5L engine, EPA rated 29mpg highway

I don't get it, bigger engine less gears and same mileage in the Malibu plus it is more pleasant to drive powertrain wise without the constant shifting and higher revving engine.


But you are looking at Highway mpg's.
Is there a greater difference between the two when considering City driving?

The number of gears available doesn't matter if top gear is only used.
 
Malibu is rated 20 city and Regal is rated 18 city. That's even more suprising.
I am going by EPA numbers, come to think of it, did they change the way they calculate? That could explain the difference maybe, in the official numbers.
I know I get about 30 in both cars on the highway.
 
It's all a game of physics. HP to weight ratio, aerodynamics, and work required. A car driving on 100% flat roads all the time will get better mpg than one that is constantly climbing mountains.

My Jeep gets about 18mpg average. I think that is decent considering I'm not light on the pedal, and its 16 years old with basically a tractor engine mated to a 4 speed auto.

My father's Grand Cherokee with the 5.7 V8 gets 20 average. Although his Jeep is larger and heavier, it has more HP, better aerodynamics, and has the ability to run on 4 cylinders on the highway.
 
Originally Posted By: dishdude
This large vehicle gets 24 MPG without me even trying.


IMO, that's pretty bad. I drove a 1995 Escort and one of the reasons why I still drive it is because newer cars don't get much, if any, better gas mileage. I don't need all the bells and whistles that new cars have, they only weigh down the car and make it less reliable. I also don't need a 0-60 in less than 14 seconds, and that's what's really holding back gas mileage.
 
Originally Posted By: bradepb
Malibu is rated 20 city and Regal is rated 18 city. That's even more suprising.
I am going by EPA numbers, come to think of it, did they change the way they calculate? That could explain the difference maybe, in the official numbers.
I know I get about 30 in both cars on the highway.

The EPA has changed how they calculate mileage, but if you get your numbers right off their site, you will get corrected and comparable mileage numbers for the older cars.
My Focus originally came with a 39mpg hwy rating but it was revised to 33mpg and that's what's on the EPA site now, and its more realistic. Highest I've got is 36mpg for a tank and 33 is more normal.
 
Originally Posted By: bradepb
Malibu is rated 20 city and Regal is rated 18 city. That's even more suprising.

The Regal is 350 lbs heavier, so it takes more effort to accelerate it, which is what you do very often in city driving, so I'm not surprised the city mpg for it is worse. That 4-cylinder turbo is getting worked hard to get that heavy car going.

Modern 4-cylinder turbos get you the performance comparable to an NA 6-cylinder if you stomp on it, but stomping on it won't necessarily result in better mpg. Personally, I prefer the characteristics of an NA 6-cylinder than a turbo 4.
 
Status
Not open for further replies.
Back
Top