My Road Speed Lessons on the Highway

[mattsk1]

Just got back from my Honeymoon Road Trip with my 2010 Mazda 3 i Sport. Got to really test out my areo mods(Side mirror deletions, Lower grill Block, and Wheel Covers), practice some hypermilling technique and find out the effect of driving with more weight and at variable speeds. Lesson learned was 65mph seemed to be the tipping point before my MPG significantly decreased. I noticed at 70mph it took much longer for my scangage to get to about 38 mpg. With the same load on the car I drove from a warm engine after vising my folks with my wife then when 60mph back on the highway to our place about 35 miles away mostly highway. My scangage went quickly to 40+mpg and got up to 42mpg at the end of the trip. I was starting to think something was wrong with my car on the road trip. That last leg of the trip helped ease my concerns.

Now I have the 35mile mostly highway commute to work and back driving at 50mph and emptying my car of clutter. It is so much easier to coast, but is not as effective going up hill. After about 30 minutes on the highway I am consistently getting to 45-47 mpg!!!. Five round trips per week of that will dramatically effect the fuel economy of my tank and looking forward to posting on my fuel longs.

The downside is our lease at the apartment is up in July and we will most likely be located somewhere further from the highway. So I will enjoy my best fuel economy when I can!

[ever_green]

If we are considering that our cars have similar displacement, frictional properties, gearing, weight and BSFC (mine is 0.43 hp/lb/hr) then I guess your car is probably much much more aerodynamic than mine. This is because from my experiments anything above 35mph starts to really take a hit on my mileage.

this a graph for my car, MPG vs. MPH



If i'm not in the mood for pulse and glide I take the slower route (side roads and such) and crusie at 35mph. Sometimes the results are better than highway P&G.

[2000mc]

http://ecomodder.com/forum/showthrea...you-15182.html

[mattsk1]

Originally Posted by ever_green

If we are considering that our cars have similar displacement, frictional properties, gearing, weight and BSFC (mine is 0.43 hp/lb/hr) then I guess your car is probably much much more aerodynamic than mine. This is because from my experiments anything above 35mph starts to really take a hit on my mileage.

this a graph for my car, MPG vs. MPH



If i'm not in the mood for pulse and glide I take the slower route (side roads and such) and crusie at 35mph. Sometimes the results are better than highway P&G.

I live in Atlanta, so 50mph on the highway is slightly dangerous when the average speed is 70+mph. I do not have US routes or state routes that I can test the 35mph with accuracy. The most I can do on those roads is doing as much coasting in neutral is I can. I might be moving the Cedar Rapids, IA soon. Their will definitely be roads that I can test the 35mph on my car to find out the max mpg per speed of my car. My car does have a low Cd of .29 stocks. The 2012 Mazda 3’s have Cd’s of .27. Should have waited for those!!!