28 MPG??!???!? You've got to be KIDDING me!!!

[ShadeTreeMech]

What i don't get is how something as boxy as a Scion can get such great fuel mileage.

[user removed]

Aero drag is 70% of your energy losses at 70 MPH.

At 55 MPH the best way I use to understand it is to just square the speed you are going.

For example
50 MPH=2500 units of drag
70 MPH=4900 units of drag
100 MPH=10000 units of drag

Increasing your speed by 40% (50-70 MPH) almost doubles the energy required to move through the air alone. Most other drag factors are linear in their relation to speed but aero is exponential, meaning if you double the speed you increase the aero drag by 400%.

Now for some people time is an essential component of travel and they might consider the fuel saved not worth the increased time spent on the highway. There is also an increased risk factor when you think about an 8 hour trip versus a 10 hour trip. as far as the possibility of an accident.

If you have choices in your trips where you can choose the "road less travelled" and go 55 MPH instead of 70+MPH, you might give it a try to see what a difference it could make. I would bet at 50-55 MPH that Maxima would be close to 37-40 MPG.

regards
Mech

[SentraSE-R]

Originally Posted by ShadeTreeMech

Guess I'll just have to piss some folks off by driving "slow"!

Now you're ready to see some real mpg improvement .

The Scion xB gets good mpg despite its .35 cD for 3 reasons:

It only weighs 2200 lbs
It has a gas-sipping 1.5 L engine that makes only 108 hp
I don't make it fight air resistance too much. 60 mph is its top speed, because anything over 55 mph hits an aerodynamic brick wall with the box. I get 32 mpg at 70 mph (@3500 rpm!), and 52 mpg at 31 mph. The secret is slowing down.

[Red Lion]

Hey Shadetree,

It's definitely possible to beat 28. I used to own a silver 96 Maxima that I regularly got between 25-30 city! You just have to slow down, calm your nerves and remember:

the guy's in the flow that come flying up behind you all angry or aggressive aren't going to do two things:
1) they aren't going to hit you, and
2) they aren't going to reimburse you the extra money at the end of the week that you saved by slowing it down.

When you start to look at it like that, it becomes easier to just let them fly by and not worry.

Tell ya what, when we get together for a hang-out, drive with me for a bit. I'm not real good but maybe I'll do something we can pick up on.

[Frank Lee]

Originally Posted by ShadeTreeMech

Frank, on the 93 tempo, does it have the old 3 speed auto the 90 model had? I know I always wished I had a 5 speed in the 90 tempo I had. 3k rpms at 60 is ridiculously high in a small car with a larger engine.

I had a Buick LeSabre that barely cranked out 2k rpms at 90 mph. It always facinated me how fast I could go at 1200 rpms in that car (about 60). And taller gears would take out some of the off-the-line acceleration that gets me into trouble to begin with.

I think the Tempo a/t was the same from '84-'94: 3 speed, no OD, no locking converter- old school.

"Blue" has the a/t and "Sport Coupe" has a 5-speed. For fe there is quite a difference between them even though all else is virtually equal.

The 3800 was a nice fairly efficient package. I'd like to put one in front of a 5-speed and see how that goes!

[ShadeTreeMech]

GM's 3800 and Ford's 300 I-6 are two engines that I think fall under the unsung heroes category, in that they are both low end torquey engines that don't ever seem to want to give up. It's sad they stopped production in '06, which ended the 39 year reign of an excellent engine. I just read the wikipedia article for the Buick 3.8L here, and it has a very interesting history. It's very similar with the 3.0L Nissan engine, which IIRC had the ability to support 600HP with the proper heads etc.

I understand progress is necessary, but some things need not be replaced, only slightly altered to keep up with the times.

[Clev]

Anybody passing a cop and going 10 mph faster is not "going with the flow" on any freeway I've been on.

[ShadeTreeMech]

lol it's a funny thing driving in Arkansas. Everyone knows you can go 10 over without getting into trouble. But when a police officer shows up, they slow down to the speed limit (or slower, if the cop is messing with their heads by going slow himself). So going past a cop while going 10 over is a lot of fun, mainly because I get out of the queue of traffic clogged up behind Smokey. True I am leave the flow behind, but it is generally in an area of lower speed anyway (ie an open stretch of road set @ 35-40 mph)

Having been pulled over several times in my youth, and having friends in the force, I've become acquainted with several of them and have talked with them. My favorite memory is being escorted to a holding area (with bars) for an unpaid traffic ticket by a genial officer. On the way there, he was stuck behind someone doing 5-10 under the limit and commented that he didn't understand why people slow down like that. I mentioned it was probably because there was a cop behind him, which he thought was mildly humourous.

It would seem to me most police are just regular blue collar types just trying to do their job. And so, despite my efforts to fund their services through additional taxes levied on me for exceeding spped limits, I do have a soft spot for them.

[Frank Lee]

Ha Ha, that reminds me of the time I came up on this gargantuan convoy of cars plodding along the freeway. I went to the left lane and when I approached the head of the train of cars I saw that it had "cherries" on the roof... but they weren't cop cherries, they were for wide loads or something. So I proceeded past... and talk about opening up the floodgates! Once I blazed that trail it was like dropping the starters' flag.

[mcrews]

Shadetree,
I have an 02 Infiniti Q45 w/4.5L v8, 340hp 3800lbs. 2.78 rear end ratio. I got 27mpg all day long on a 300 mile trip BEFORE I got here.
Couple of thoughts:
1. do not turn your engine off while driving ANY AUTOMATIC.
2. You can coast in nutral w/ the engine on and you will do just fine. I have 194,000 on the Q and I have coasted for yrs. And still have a great working tranny.
3. GET A GAUGE. THe Q comes w/ one and I use it like a video game. It really helps. I have also bought a scan gauge. I recently got 30mpg on a trip to and from sacramento ca to fresno, ca
4. It's all about rpm. I run 255/45/18 on the stock rims that came with 245/45/18. the 3% increase in diameter helps lower the rpm.
5. Look for my post on underbelly pan. I also block the front grill.