Mods for speeds 35-45mph?
 

What modifications can be made to increase FE on vehicles with auto trans? That is besides the usual stuff. I.E. Increase tire pressure, lower driving speed etc: Most of my trips are 20-25 mile in length with speeds between 30 and 45mph. The best I can get is 27-29mpg. Would like to get 30+.

Mike

Hello Mike,

Are you coasting down hills in neutral? Do you have stop lights where you can turn off the engine? Are you avoiding A/C and daytime lights? You could see some benefit from some aero mods. You might want to get a ScanGauge and use it to maximize your mileage while accelerating.

Try 0w-30 synthetic motor oil and synthetic tranny oil. It made a difference for me.

Here's how I would order the mod priorities:

1) your driving style/habits
Read the 100+ tips (again)
Get a scangauge (or some other way to get instant feedback on MPG)
reduce idle time
reduce accesory usage (ie A/C)
get to your most efficient speed ASAP

2) engine maintenance
oil/oil filters
spark plugs
fuel type


3) tires
low rolling resistance type
proper air pressure
proper alignment

4) weight reduction
if you don't need it, dump it

5) aero
"smooth" out the car's profile by covering/removing anything that creates bad drag
-grill block
-smooth hubcaps
-belly pan
-front air dam
-rear wheel skirts
-side/front/rear wheel fairings
-wiper wind deflector
-remove passenger side mirror
-remove racks

I have done most of the tried and true methods of hypermiling because of the auto trans I do not shut engine down at long lights but do put trans in neutral. I have blocked the front grille on the outside but this would only help at expressway speeds. I use 5-20w full syn eng oil and do not have a lead foot. I have ordered a KIWI and am hoping that it will help me achieve better FE.

Mike

You can shut down the engine at long idles. I use the 10 second rule. It's with forced auto stops and pulse-n-glides that we shouldn't do in AT. Sometimes a lead foot early can be better than a limp foot because you want to get to your highest gear sooner than later.

Definitely driving style tweaks will help the most.

Don't underestimate the effect of aerodynamics at low speeds. When I put on my above-bumper grill block I immediately noticed subjectively longer glide times at in-town speeds (60 km/h = 36 mph), whereas at highway speeds the drag effect was actually less noticeable (except that the car feels a lot more stable, less nervous). Even at very low speeds (25 km/h = 15 mph) something's happening because raindrops dripping off the front lip of the hood get blown back toward the windshield, that didn't happen before the grill block. A rule of thumb says that above 60-80 km/h (36 - 48 mph), depending on the car, aerodynamic drag becomes larger than other drag, but that means that below that it's still up to 50% of total drag.

And raising the tire pressure helps, too.

Wow, Im sold on areodynamic mods now.
Most of my daily commute (40 miles daily total)
is 40 to 50 mph. I need to get started on the front air dam,
and complete underbody pannel.

Hi,

Can you post a picture of the front of your car? I'll bet that a grill block and/or blocking some other "features" would help.

My mild aero mods definitely helped at 40-50mph, where almost all of my commute is. In particular, this is a good situation where cheap mods will really pay off, too, since the benefits might not be huge, but they're still there to be had.