It's all about dynamics and initial inertia, once it's a rolling load the running savings are negligible apart from the narrower tires and road friction saved which is also negligible. The additional costs do not warrant the savings IMHO and if you have a puncture with no spare wheel it's a lot of time wasted waiting for a tow truck. Unfortunately the D2 is not exactly aerodynamic more like pushing a house brick through water and that is a serious cost to fuel economy.

 

Solid rims actually get worse gas mileage than spoked rims, or so I've heard. Aerodynamics is weird.

 

Sell the V8 and buy a TD5 diesel and you'll double the MPG and reliability overnight.

 

get a stethoscope and listen for any dragging bearings too (alternator, tensioner, water pump, etc). getting rid of parasitic power suckers makes a big difference

 

Ya, like 0.01 mpg. It’s a heavy, outdated technology vehicle. It gets the mpg it was designed with

 

would removing the AC help?

Also...while small gains I would suggest a K&N air filter

 

Stock bumpers and air dams, no roof rack , and keep it under 70. I could get 17 mpg on the highway in a 5 speed with that combo.

The engine is just really inefficient from its poor combustion chamber, bad port design, and flat lifters requiring heavier oil than modern stuff.

 

I have ac removed and a K&N filter. They don't make any difference at all on any modern vehicle, including these Discos. Those made a difference back in the day of carbs and ac compressors that ran full time

 

Never heard that before, nearly ever prototype fuel saving car I've ever seen...uses a closed rim (like pictured below). Even cyclist realize the "egg beater effects" and ride with nearly enclosed rims on time trials (where drafting isn't allowed and you want as little wind resistance as possible).





Egg-beater effect affects efficency by pos/neg wheel rotation. When moving forward, the bottom of the tire is going away from the direction you are moving (positive wheel rotation), but the top portion of the wheel is moving into the direction of travel (negative wheel rotation). Basically beating the spokes of the wheel against the oncoming air, causing egg beater effect and reducing efficency. A smooth outer disc shape wheel eliminates this effect.

Also, a/c compressor have had an electric clutch mechanism for as long as I can remember (forty years of being a mechanic). I've never seen, or heard of, an a/c compressor that ran continuously. Yes, the pulley turns continuously...just like an idler pulley...but the compressor is not engaged.

Brian.

 

It doesn't justify the cost vs savings.