“Be kind, for everyone you meet is fighting a hard battle” - Often attributed to Plato but likely from Ian McLaren (pseudonym of Reverend John Watson)

Tuesday, June 26, 2007

Taming the LR3

As I've mentioned repeatedly, I have had very little success in utilizing driving techniques to make a large impact on the fuel economy of the LR3. This lack of success led me down a road of trying to understand the aerodynamics of the vehicle, the specifics of the engine and transmission, and the effects of driveline friction. It's been educational, but not satisfying with respect to enabling me to goose my gas mileage.



As my brother said, "it kinda takes the fun out of it." Hence, for several months, starting around the beginning of 2007, I stopped using fuel economy maximizing techniques. I didn't go "hog wild" and floor it from the light, drive as fast as traffic would allow, etc., but I would accelerate with the traffic, drive at typical speeds, eschew coasting in neutral and turning off the engine, etc.



The last three weeks or so, however, I have renewed my efforts. I've managed to bring my three tank moving average of gas mileage from a little under 16 m.p.g. to a little under 19 m.p.g. My most recent fill-up indicated 19.37 m.p.h. The improvement is probably a result of 55 m.p.h. or slower, drafting where possible, stoplight shutdowns, and coasting with the engine off. I did most of these before, but I tried being ultra aggressive in doing them.



So fuel can be saved. The LR3 is rated by the EPA at 18 highway, 14 city. By my best estimate of the relative amounts of highway and city driving in my regime (about 60/40) the EPA thinks I should see overall mileage of 16.4 m.p.g. (0.6*18 + 0.4*14). That means that the 18.85 m.p.g. in my most recent three tank moving average is 14.9% over the weighted EPA estimate.



As a point of comparison, in the Jeep Grand Cherokee Limited in which I started this experiment, I was able to achieve about 30.6% better mileage than the weighted EPA estimate. I don't know the reason that the LR3 has only allowed me to exceed the EPA estimate by about 1/2 as great a percentage as the Grand Cherokee. It may be that the LR3, about six years newer, incorporates engine management techniques that make the vehicle more efficient when driving normally. If this is the case, I will have to assume that all manufacturers utilize these management techniques and hence reduce my estimate of the impact on national fuel consumption of universal adoption of extreme mileage enhancing driving techniques. I'll save that for another post.



I will say that I am pleased that I can exceed the 19 m.p.g. barrier, and 20 m.p.g. is in my sights.

2 comments:

bobh_ said...

FYI,

I have a 2007 model with 4000 mi on it. We love our "GRROVER". I just got rid of our p/u to buy a Prius for work, would you believe?!
However, last week had one decent day here in the PNW and I talked my wife into swapping cars. She drives 6-7 miles one way to work; I drive 36. She gets 16 mpg with A/C; I got 23.7 with no A/C, 60 mph and no wind to speak of. LR designed this car to get about the same mileage with or w/o A/C. I find that cruise control helps a lot, as well as common sense driving. In addition, I use only quality premium gas. What a wonderful car to drive! It is not a truck!!!:)

King of the Road said...

I really do like the LR3. It's driving characteristics are excellent and it's comfortable and roomy. I haven't had maintenance issues with it in its 32,000 miles. It's not a sipper of gas, however.

My current 3 tank, 5 tank, and 10 tank moving average mileages are 20.86 m.p.g., 20.33 m.p.g, and 20.01 m.p.g. respectively and I utilize every method and ploy I can think of to minimize fuel consumption.