Quote:
Originally Posted by racprops
No boat tail...what about deflectors to bend air into the void in back??
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Without wind tunnel testing, these are more likely to do harm than good. Better to take anything and everything off the exterior of the vehicle that can cause turbulence.
My car comes stock with:
-Partial belly pan, mostly smooth underneath
-Air curtains for the front wheel wells
-Very smooth, non-spoked alloy rims
-Rear wheel covers
-Deflectors near the exposed parts of the rear wheels
-Recessed windshield wipers
-"Boat tailed" rear end, with a gentle taper that follows the shape of an airfoil
-Narrow, low rolling resistance tires, with a high recommended pressure
It was EPA rated for 70mpg highway.
On my car, my exterior aerodynamic modifications include:
-Removed mirrors and replaced with cameras / screens
-Removed rear wiper (it's in the wind stream on my car)
-Removed antenna, antenna base, rear washer nozzle
-Blocked 100% of upper grille, block 50-100% of lower grille depending on weather
-Full belly pan, front to back
There's probably some other stuff I can't think of right now. I can break 100mpg on the highway now, and have had tanks as high as ~85mpg. So, I know what I'm doing works.
Other things that are proven to help are pre-warming (e.g. oil pan and block heaters), lighter weight lubricants (I've run 0w16 oil), electrical load reduction (LEDs), warm air intake (for gas engines), higher temperature thermostat (somtimes), kammbacks, engine kill switch, accessory delete, weight reduction.