Prepping for 5000 miles of highway. Extra mpg tips.

drive as slowly as is safely possible and pump up the tires. make sure the oils is at a correct level, clean/replace the air and cabin filters, add a boat tail

 

bisco - We're looking at a 2500 mile trip to MN and back later in the year. Do we add half a boat tail?

 

No it won't be.
And if you go restricting the air intake at the grill during the summer time........you likely will be SORRY.
What might be "worth pursuing" is: SLOW DOWN.
If you can' t bear to do that, then take what you get and don't worry about it.

 

make sure all your aero panels are fastened securely

 

Wash the car and put a nice slippery coat of wax on it. That will very slightly reduce drag.

 

We go coast-to-coast every other year and here to Colorado on the off years. In fact, we're leaving the first week of July for North Carolina, Michigan and back.

You can boost mpg a little with a good wax job, making sure tire alignment is good, boosting tire air pressure, not carrying excess weight, etc. but be realistic about what return you will get against the cost of anything that's going to cost you money. Raising the gas mileage from 49 to 55 is only going to save you about $33 in fuel at $3.00 a gallon.

Driving conservatively is going to save you the most. Go easy on the uphills so you don't wind out the ICE. Stay at the speed limit or a touch below the rest of the time if you really want to maximize mileage but it will obviously be at the expense of your time. There's nothing wrong with relaxing and sticking to the right lane with the truckers. That way your hybrid battery doesn't get very taxed, saving the weaker cells from failing.

Mainly, don't sweat it. Relax and enjoy the trip. Fretting about an mpg number while you're out there will only drive you nuts.

 

There is no magic.
Make sure the tires are up to pressure.
Make sure there aren't any panels flapping around loose, including underneath.
There are no "techniques" that will make any measurable difference except the standard maintenance items.

I wish you luck. I hope you belong to an "automotive club" for towing if necessary.
I would be more concerned about being able to complete the trip without a disabling fault showing up than I would be about the gas mileage.
Slowing down will decrease the odds that something breaks too.

 

there are several expert threads here on the matter, along with the advice directly from the company

 

There is no magic for "reconditioning" a battery once it's useful life is over.

And as you have found the hard way, sometimes you do more harm than good.

 

Find out the elevation through the mountains during the route. At certain elevations, you can use lower octane gas, and save a few $'s. Know how far you can drive before you have to return to higher octane gas. I didn't know, so I had to use the recommended octane, since I didn't want to have low octane gas in the tank at lower elevations.

 

Yes. At higher elevations 85 is usually the lowest grade and 87 is the middle. I'm a little hesitant to use it, though. From fueleconomy.gov :

Selecting the Right Octane Fuel

"What is 85 octane, and is it safe to use in my vehicle?
The sale of 85 octane fuel was originally allowed in high-elevation regions—where the barometric pressure is lower—because it was cheaper and because most carbureted engines tolerated it fairly well. This is not true for modern gasoline engines. So, unless you have an older vehicle with a carbureted engine, you should use the manufacturer-recommended fuel for your vehicle, even where 85 octane fuel is available."

 

Clay bar and wax everything including the windshield.

 

Waxing a car does not reduce its aerodynamic drag. At the speeds road cars travel, there is a no-slip condition between the body and the air flowing past it, i.e. the the body and the "layer" of air next to it do not move relative to each other. As you move away from the body surface, the speed of the air increases in the boundary layer until you reach the freestream velocity outside of that boundary layer, which is the airspeed of the car.

Blocking intake area will reduce drag; in fact, I was just reading a 2012 paper by a group of Tata Motors engineers who found that completely blocking the intake of an Audi A2 reduced its drag coefficient by 0.031, or more than 10%. Make sure you have a Scangauge or app so you can monitor coolant temperatures and do a few test runs with various amounts of the grill covered before you go to see what works and what you're comfortable with.

If you're really ambitious, you can remove the passenger mirror; no state requires an external passenger mirror (except a handful that require it when the windows are tinted). My car hasn't had external mirrors since 2016, and my previous car since 2012; most states don't require one at all, including Oregon. I use these:



Don't put luggage on a roof rack or anything; keep it inside the car. That sort of thing is massively disruptive to the aerodynamic profile.

Taping panel gaps doesn't usually show any benefit except around the hood, where it can prevent high pressure air from entering the engine bay around the headlights and hood sides. The Prius already has weatherstripping on the front edge of the hood and across the back for this reason (at least, the Gen 3 and 4 do. The Prime goes even further and has factory weatherstripping on the headlights and hood sides too).

At 70-80 mph, using the climate control will be more efficient than cracking a window (and more comfortable).