1000 miles on $30 of gas?

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Jan 8, 2009
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My MIL is turning 90 next month and I thinking about which car to take to make the 1000 mile trip, if and when they lift the stay at home orders. I'm tempted to take the Fiesta just for grins to see if I can make the trip on $30 of gas. Gas is currently $1.35 at Costco here. It's actually got pretty comfortable seats and a good radio, offset by a lot of road noise. But I was wondering whether its a good idea to run this little 3 banger ecoboost at 75 mph for hours on end?

I found a website that you can calculate hp requirements for a given speed and vehicle parameters. I input a drag coefficient of .38, 23 sq ft of frontal area, 2900 lbs loaded. It came back with the following HP numbers

50 mph = 11.8 hp requirement
75 mph = 31.7 hp
120 mph = 115 hp

Given the engine makes 126 hp before deducting transmission losses and it probably can't do 120, this is theoretical calculation is still probably ball park..

Then I calculated specific fuel consumption using the above info and knowing that the car gets 70 and 39 mpg at 50 and 75 mph respectively (I kid you not).
I got 0.0605 gallons per hp-hr at 0.0600 gallons per hp-hr at 75 mph. Perhaps plausible.

So 32 hp equals 25% of maximum output. Doesn't seem like its stressing the engine too much, but it does seem like 75 mph is the tipping point where the engine starts to sound like its working hard. And this is flat land hp, hills (and wind) will require more hp.

How much is too much in pushing an engine?
 
I could do it for under $20 with one of my cars.

[Linked Image from fototime.com]
 
The makers run them on a track for hours at full throttle as part of proving the design. It will be fine, you may very well notice it runs better when you get back from your little Italian Tune Up.

Of course, change the oil first. Or not depending on who you want to believe. Use gas PEA additive and change oil when you get back, or not.

It will make no difference. Do however check the oil. And check it again at the first stop, sometimes this gets the oil hot and it gives up fuel and water, so you can go low.

and have fun.

Rod
 
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First, oil filter is listed as Fram 3614...
If you have room, a Fram 3600 or equivalent is same base, and bypass, only an inch and a half longer...

Second, check your tires.
Look on the sidewall for "Max Inflation"
While the ride will be rougher, if you inflate to 5-8 pounds under the max, you will get better mileage.

My Smart has 51 psi max tires, I put 44 rear, 37 front.
OEM pressure was 29....

Fill the coolant bottle to the "HOT" line, when the coolant is cold...
 
LOL you honestly thing 75mph interstate cruising is bad for your Fiesta?? C'mon, they were DESIGNED for that. Its much easier on them than short trips and stop-and-go!

Do a fresh oil change and hammer down! Just do us all a favor and don't hypermile, most of us don't have time to wait on you taking 20mins to get up to the posted speed limit on an entrance ramp.
 
OP,
I did Chicago - Atlanta - Chicago in an '08 Toyota Yaris sedan with 2 adults, 2 kids and luggage.
No problem in the TN/GA mountains and it never run better.

Keep the tire pressure at 4-6 PSI more than mfg recommended (you don't need to feel everything on the road or ride like on iron wheels), choose large chain gas stations, use a pair of apple headset (just to plug in some of the road noise, but still be able to hear everything around you), have some sunscreen, good sunglasses (aren't you in Texas?), clean your windshield and have some fluid with you (bugs, dust).

Enjoy the view and drink enough fluids (but not that much to stop every 15 minutes). If you enjoy it, you can drive more, maybe even in one shoot.
 
No problem cruising at 75 in a modern vehicle all day. I think you can do it easy. And if not it's only going to take a couple dollars more in gas.
 
Originally Posted by A_Harman
How much rpm is your engine running at 75 mph?


I'd guess about 2700.

I'm just thinking that this car seems in its element around town and gets better on city mpg than highway - I mean relative to larger cars, not in absolute terms. When I see the mpg drop so significantly with speed, it makes me wonder if the 3 banger is more loaded up.

50 mph = 70+ mpg
60 mph = 60 mpg
70 mph = 43 mpg (~?)
75 mph = 39 mpg
 
Originally Posted by Ihatetochangeoil
So how do you MERGE onto an Interstate? (Don't even dream of passing uphill)


The HP-to-weight ratio is pretty similar to a normal car and in fact the turbo 3 cyl is lighter, more powerful and faster than the larger NA 4 cyl fiesta. Its just making a lot of hp from a tiny engine. As much HP per ci as a Ferrari, it just doesn't have many ci's.

Amazing what they do with technology in economy cars.
 
Originally Posted by Burt
Originally Posted by A_Harman
How much rpm is your engine running at 75 mph?


I'd guess about 2700.

I'm just thinking that this car seems in its element around town and gets better on city mpg than highway - I mean relative to larger cars, not in absolute terms. When I see the mpg drop so significantly with speed, it makes me wonder if the 3 banger is more loaded up.

50 mph = 70+ mpg
60 mph = 60 mpg
70 mph = 43 mpg (~?)
75 mph = 39 mpg


32 hp at 2700 rpm => 62 lb*ft of torque. That's pretty heavily loaded for a 1.0L engine. But that's the intent of engine downsizing.

According to the road load data in your original post, your car requires 11.8 hp at 50 mph, and 31.7 hp at 75. That's 168% more power required for only 50% more speed, but the car only loses 43% in fuel economy. The bsfc values you quote shows that the engine is running at about the same thermal efficiency, actually a little better at the higher power.
 
I think you should drive slower that 75Mph if you want to make sure you can do it with a max of $30. Does the car show you how many MPGs you are getting?
 
I try to air tires up to max stated on sidewall / better MPG . Never had any problem . If worried , check the oil level frequently .

I try to remember ( in town ) to check it every time I fill the tank .

Check the rubber ( hoses, belts , wiper blades ) before you start off . Do not forget air pressure in the spare .

Check all fluids .
 
I drove a 1.25L N/A Fiesta in Italy at speeds over 130kph (where I could get away with it) for the better part of a day and it seemed happy to do it.

People have been driving small displacement engines at high RPMs all over the planet for generations without drama.

You should be able to do this and as long as the car is filled with the proper fluids and the radiator is working to specification, nothing bad will happen to the car.

Depending on how loud it is, it may be harder on you than your car.
 
Car will be fine.
The question is: What kind of shape will you be in after 1K miles in a Fiesta?
 
Depends where in Texas. Deer hit at 75 mph in a Fiesta would not be good. You are actually taking more bodily risk to save a few bucks (no pun intended). However, if you want to be scientific, your oil will heat up at a constant 2700 rpm so maybe you will want to go up a grade. Make sure you buy your snacks and drinks at a discount store prior to the trip or they will contribute big time to your expenses. Take some pics and do a selfie at the end of the trip.
laugh.gif
 
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Originally Posted by Tdbo
Car will be fine.
The question is: What kind of shape will you be in after 1K miles in a Fiesta?


This^ driving to dallas for me is 154miles. There and back is around 308 miles. Interstate 35 paired that with my ladys 2012 Fiesta hatch" its like you just got beat up when you get there and by the time you get home? Youre exhausted. Although sleeping afterwards is great, that car is physically exhausting to drive.

Never had that issue with my 13 Dodge Dart, 16 Veloster Turbo, or my 18 1500
 
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