I live in PA and I took my family down to Williamsburg, VA this weekend. We wanted to take my wife's new xB because of the extra room, but it only has 200 miles on the new engine. I know there is alot of debate on here about proper engine break-in, but the owner's manual says that for the first 1000 miles, you should avoid driving at any one speed for an extended time. That's exactly what highway driving is soooooo.....
we took my xA.

The trip was a 4 hour drive each way. It was me and my wife up front, and our 12 year old son and his friend in the back (both boys around 120 lbs), plus a full load of luggage in the "cargo" area. I was very impressed with my little car on this trip! It rode great, had plenty of power and plenty of space for everyone. We never felt like we were in a small car. The boys watched movies on our portable DVD player the whole drive. I averaged between 65 and 70 MPH most of the time, and had the A/C on almost the whole time too. And even with the A/C going and a full load, I still got 36.5 miles per gallon! I love that car!

 

That sounds great! Couple of questions though, do you have factory steel wheels, other wheels, auto or standard?

 

I have 16" wheels with Falken Ziex ZE-512 tires. They weigh a tiny bit more than the stock steel wheels, but not by much. I was careful not to buy heavy wheels. The car is a 5-speed manual. I was really surprised to get that good of milage on the trip because to be honest, I have been a little dissapointed in my daily "average" milage. Most of my usual driving is all in-town stop and go driving and I've been getting around 31 MPG. I never expected to get 36.5 on the highway with a full load and the A/C on.

 

At highway speeds, I actually get better milage with the car loaded. For my last move, I drove from IA to RI with my 91 camry LOADED TO THE GILLS! I mean, I was literally pouring stuff into the leftover spaces.

Got 36MPG, best I've ever seen. My Theory...

When you are not making starts and stops, extra weight actually works in your favor. The inertia keeps you moving, and the extra weight resists winds, road friction, etc.

Just my theory.

 

With my xB, I dropped from an average of 33MPG a tank
to 28-29MPG when I went up to Chrome Plated 17"
wheels. Unfortunatly I don't have a scale to tell you how
much the weight difference is.

I can't wait to take a long trip with the girlfriend though!

 

That's not a bad theory and I'm sure it could have something to do with it. I don't think that theory would apply if your trip involved a lot of up-hill driving though.

 

i do a lot of weekend travelling myself and had two buddies and a FULL load in the back... had the 60% folded down and could barely see over the top of everything out the back window.

long story short, got behind a woman doing 45 in a 55, we were running behind, and I went out on a pass that made my passengers nervous (oncoming car ~300 yards out) until they felt the car's get-up-and-go when i downshifted. they were dead silent on the pass, and when I pulled into the lane again I got a "wow, nice power on the downshift" and a very impressed "holy $#!^!!!!!" They still didnt believe me when I told them how many horses were under the hood and how well it handled pulling all the weight we had in the thing

 

Yeah. . . about A/C (on the highway), there was a study a few years back that concluded that at highway speeds, running the A/C is more efficient than rolling down the windows. Supposedly the excess drag/turbulence is more of a parasite than the A/C. And of course this is more applicable and effective at higher speeds.

 

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
sid is very very correct
as well as we have a/c that electronically lessen the a/c's clutch to give you more power when and if you need it.

 

also if you lower the car i noticed about a 1-2 mpg increase...i know its not much but now it doesnt look like a shrunken wagon and it gives it a more agressive stance

 

"When you are not making starts and stops, extra weight actually works in your favor. The inertia keeps you moving, and the extra weight resists winds, road friction, etc."


I had to chime in here. The notion that extra weight resists wind and road friction is fairly silly. You will have the same drag since the shape of the car hasn't changed, and rolling friction will actually increase due to a larger contact patch with the tires on the asphalt (more weight, larger patch). No big deal, just a friendly observation.

 

But, and correct me if I'm wrong, because the mass has increased, that friction will have less effect on slowing the car.

 

The short answer, a heavier vehicle is ALWAYS less fuel efficient. The long answer:

This is a tricky subject. As we all know, a heavier vehicle is more difficult to move (so it takes more gas to accelerate it). According to the laws of physics, an object at rest will stay at rest, and an object traveling at a velocity will remain constant at that velocity, unless a force acts upon those objects in either scenario.

Now when you move the heavy mass, you will store up the energy in the form of momentum. That's why it's harder to stop a heavy object (like a semi-truck).

Now when a force acts upon the heavy mass (ie friction or wind), you will have to counter the force with an equal and opposite force to remain at a constant velocity. TRUE, it any force acting on you will have less effect, BUT, you will have to press the accelerator harder to speed back up to your original speed. Of course this happens simultaneously, so you don't really observe it.

THis is a very simplistic, and horrible explanation, but I know what I'm talking about. . . I'm just bad at explaining it. Momentum works as a buffer, and in the end, because of the law of conservation of energy, you don't see any gains in efficiency. The fact is that it takes more energy to move a heavier mass. You do have more momentum when you are up to speed, but you have to remember that momentum works both for and against you at the same time.

 

can't you some what improve the mpg by lowering your car too slightly improve the coeffect of drag?

 

Hornet, I think you meant coefficient, right?

In theory, yes, lowering your car would reduce drag and improve mileage. There's a patch of turbulent air beneath the car that almost acts as a solid piece of car that you're essentially fighting to move with you as you roll along. However, I'm guessing here, but I'd think any improvement would be neglible w/such a small difference in ride height.

I'd bet you'd see a more significant change (for the worse) w/adding a 4" lift to a 4x4 Tacoma, etc., b/c they simply bring along a lot more turbulent air beneath them.

I, like you, am hopeful that I'll see a MPG improvement when I install the Tein coilovers on the xA, but it's just that, hope. Though, maybe on a long trip you'd notice. Hard to say. I'm eager to find out.

 

Which goes back to my original assertion: at constant Highway Speeds, like when I was driving cross country. my overweight camry was as fuel efficient as your unloaded xA.

 

I drove up to the mountain twice last week plus back and forth to work and got 35mpg, with the AC on high, only 1500 miles on the car, very happy with thoughs numbers.

 

I really like the split seat with the flat floor when folded. My old Omni had about as much space, but the rear seatback folded in one piece, and not only didn't go flat, it wasn't even level with the rear-most floor.

Anybody have rough dimensions, width and depth, of the hatch area with the seats up?

 

I believe you misread my post. Actually, a loaded Camry will have substantially worse gas mileage than an unloaded xA. However, a loaded xA may or may not see better mileage than an unloaded Camry. I don't believe you actually read my post.

 

1. Momentum = (Velocity)(Mass)

2. Momentum - Friction = New Momentum = (New Velocity)(Mass) = slower
From this equation, you can gather that a heavier vehicle will lose less speed from friction alone.

3. New Momentum + (force/mass) = original momentum = Original Velocity.

The equations are a bit crude (and probably with some errors), but the point is that it takes more force in the massive vehicle to remain at a constant speed, even though the changes in speed are more subtle.