[Texas] Fast Roads -- What To Do?

Being safe is more important than good gas mileage.

If there are no alternatives to driving on this road, then do the same speed as other drivers.

 

It is by Bob Wilson on an early 2010 Gen 3 Prius. Bob works with NASA, not a dealer. There may be minor software improvements between a 2010 and a 2013, but most will be applied to the older cars as they get dealer service.

Bob's chart is for steady state MPG when tested in two directions without wind, getting up to that speed, traffic, weather, etc. would all lower that MPG. I routinely see 55 MPG cruising in my v, but my average MPG is 40, as I never wake up already cruising.

 

Jimbo covered it well.

Just drive as slow as you can safely. You'd be amazed at what you can get away with once you get out of the fast lane. I used to think you can travel no slower than 80mph safely. Now I drive 60mph in most cases. 65-70mph when I have to. My last trip to LA (389 miles) at 75-85mph during cold/rainy weather was good for 45.7mpg indicated.

Air up your tires to at least 38psi and as much as 44psi if the roads are smooth.

Keep your A/C turned down (78F+ setting) during the summer. Or learn how to live without it.

Do NOT get 17" wheels.

Find a big rig that you can use as a blocker to allow you to drive slower without annoying other drivers but do not fully draft him.

Use the most fuel efficient tires available (Energy Saver A/S).

Learn how to glide whenever possible to mitigate for the times you have to drive/accelerate fast.

 

^ Lots of good points above. That's the thing I guess, do what you can, when you can. In particular I like tucking in behind a slow-and-steady truck: "What can I say, I'm behind him..." .

You have to wonder when we're in danger of being run off the road, for obeying the law.

 

If you get 40 MPG driving Prius at 80 MPH, it's still better than driving Corolla at 60 MPH. On the other hand, if you want to race the other cars, maybe think about a Porsche?

 

I drove across Texas just last weekoin those same 80mph limit roads. I never drove over 74mph and didnt feel like I was being unsafe. Just move out of the passing lane and let everyone go around you. I laughed at most of them thinking knowing that their mileage wasnt near as good as mine and I was only going a few mph slower than them.

 

Lets reverse that, if you were Toyota, would your liability lawyers allow you to build a car that was not safe as fast as it would go?

I do not think it is coincidence that the Gen 2 Prius is limited to the top safe speed of it's tires, for instance.

Tire code - Wikipedia, the free encyclopedia

 

Be sure to wave at them at the next gas station . . . use all fingers.

Bob Wilson

 

I'm the guy who plotted MPG vs mph for my wife's new 2010 Prius:

You can improve the high-speed performance by:

• reducing aerodynamic drag - there are several 'low hanging' fruit but you car might look a little 'funny': (1) reduce cooling drag at high speed, (2) after-body boat tail, (3) leading and trailing tire aero-shape, and (4) wheel-well covers.
• reducing transaxle drag - after 1-5k miles, have the transaxle oil changed to remove left-over manufacturing debris and early sealant contamination.
• reducing rolling drag - change to lower rolling resistance tires (aka., high-pressure, 51 psi) Sumitomo T4s are what I use, (2) four-wheel perfect alignment, (3) larger diameter tires (not a wheel change), and (4) minimize internal weight (strip everything not needed, needs to be at least 10% or about 300+ lbs.)

My recommendation is:

• Get the car and baseline its performance.
  • Begin a mileage log to track performance (trip is best, daily is good, per tank OK)
  • Add better vehicle instrumentation, recording preferred, diagnostic is ideal
• Study what others have done to improve performance such as ecomodder.com for vehicle mods.
• Make one change and measure the effect.
  • If no significant change, discuss the results and back it out.

This is called 'tuning the car' and is not something done over night. A typical change will take at least a week to quantify. Patience and persistence pays off. BUT managing 'user expectations.'

• 40 MPG @75 mph - baseline
• 44 MPG @75 mph - 10% improvement
• 48 MPG @75 mph - 20% improvement
• 52 MPG @75 mph - 30% improvement
• . . .

If you are expecting 80 MPG @75 mph, it is not going to happen with our Prius body. Now if you'd just transplant the drivetrain into a kit-built body . . . hummmm. Say something that looks like this:


But as you learn how to drive calm and find opportunities, you should be able to get impressive mileage without spending an arm-and-a-leg. But there is a 'wild card,' all electric. You didn't mention the range but if you could use a Leaf with recharging at each destination . . . problem solved.

Bob Wilson

 

Just finished a 395 mile trip primarily on interstate I-10, State Highway 71 and US Highway 183 in Texas along with some urban driving in Houston, Tx. I-10 has a 75mph speed limit and SH 71 is 75mph outside of cities/towns. US 183 varies from 65mph to 45mph through cities.

MPG on the Prius computer was 52.7 and 52mph average speed for the entire trip. Spent most of the highway time at around 70mph and had brief periods of 80+mph for passing. Headwind driving southeast on SH 71 and then a tailwind and later a headwind driving northwest on SH 71/US 183. I coasted as much as possible on intermittent downhills.

Buc-ee's in Bastrop, Tx ROCKS! Regular gas at $2.99/gal yesterday.

- Spindifferent

 

I don't see the problem. If you drive 75 MPH in your Gen 3 Prius, you'll get better mileage than any other car that you would drive on the same road at the same speed.