Why hasn't fuel mileage increased over the years?

Question

I was looking at new F150s online. When I looked at the '08 window sticker and compared it to the one from my '96 I was shocked. My '96 was listed at 15 city and 19 highway. The '08 was listed as 14 city and 20 highway. My '96 has a 5 speed manual trans with a 4.9L engine. The '08 has a manual trans as well, but only a 4.2L engine. Any ideas? I've always tried to buy American products but this really irks me.

Answer 1

Two trends have been consistent over the past 10 years.  One, the market has demanded MORE horsepower.  More horsepower requires more fuel consumption; there's absolutely no way around that.  Two, the market has demanded cars and trucks that can withstand an offset head-on collision with another bigger car or truck.  This means a lot more heavy metal under the sheet metal, which not only adds to the weight, but also typically means a less aerodynamic profile.

We've been governed by our fears and love of power.  The Ford Ranger of the early 80's got amazing gas mileage, but we'd never see such a truck in todays market; in fact, they're doing away with the Ford Ranger all together.  

My advice is to trade in for a new Chevrolet Colorado.  With the 2.9L 4 cylinder engine option mated to a 5 speed manual transmission, it gets an impressive 20 MPG highway/26 MPG city mileage rating, while still delivering acceptable power.  You would probably find it's just as useful as the Ford F150 for most truck needs.

Answer 2

It takes a set amount of energy to move a given weight  a specified distance. Any machine will have a  point at which there can be no further gains in efficacy.

Internal combustion engines have reached the point that no further gains can be made due to energy loss.

At this point in our technology, the only gains in MPG have to come from weight reduction in our transportation. Which has been hampered by safety mandates.

The SHO comes to mind, the 1989 model year was the lightest because it lacked safety equipment required in latter years. Just the air  bag system added about 100 lbs to the car.  This was equal to about 6 hp and there was a corresponding drop in MPG and performance.

Side impact bars, air bags and increased consumer comfort items has hampered any increase in MPG.

Answer 3

Technologically we are near the limit of fuel efficiency for the gasoline engine.  Any further gains are going to be much more expensive, incremental, and require additional power sources like electricity (hybrids).

What is the weight difference between the 2 trucks?  If they are nearly the same weight it still takes X amount of energy to move W amount of weight.  Gasoline has a fixed constant amount of energy in it that has not changed in the last 100 years.  

In 1972 laws were passed to improve the efficiency of the US car fleet.  The efficiency increased for about 10 years then leveled off.  Since both trucks were built well after 1982 their efficiency is about the same.

Answer 4

There is likely a weight difference in the two trucks. the new fords are quite a bit larger then the older 90's models. any time you add more weight to the car your mileage goes down. this is the most likely cause for the difference in mileage. Also the Fed gauges MPG differently now then they did in the 90's. this is also a contributing factor.

Answer 5

Because fuel has always been cheap, but not any more.

Answer 6

This is more generally speaking for all makes and models, not just the F150 but public demand for size, comfort, and safety has increased substantially.  The automakers, catering to our demands as we are the ones buying their products, have made the vehicles larger, equipped them with more gadgets and options, and added safety items such as 4, 6 or even 8 air bags in some cases to vehicles which may only have had 2 air bags 15 years ago.  The penalty for adding this size and equipment to a vehicle is that it makes it heavier.  A heavier vehicle uses more fuel.  

So, even with the advances made to engine design over the past few years, fuel economy has not generally increased.

Answer 7

There are physical laws involved here that you must consider. To propel X weight at Y speed takes a given amount of energy. How the energy is developed and delivered is the key. I'm sure they can build a truck that can get 55 MPG, but what do you give up to get to this point? You would have a truck that couldn't tow 800 pounds or haul it either. Now you have defeated the idea behind buying a truck. Until technology advances far beyond what is available today, a 55 MPG truck with capability would be cost prohibitive. Would you give $92,000.00 to $107,000.00 for a vehicle like that? You now have a different looking Prius.

If mileage is why you buy, buy the Prius. If capability is what you seek, buy the truck.

Answer 8

Manufacturers are fighting a number of factors: Friction in the engine, necessary gear ratios to gain power, and drag created by the size and shape of the vehicle.