[Shotimes] My MPG Test is Working!!

[krazgeo@comcast.net]

"We're on the road now.....

Speaking of which.....Yay!!  It works!!  (The idea of larger tires to get economy.)

We're on a week's trip to NE California and Crater Lake.  The first day took the GS from home to South Lake Tahoe via Hwy 50, which is two lane much of the way up the hill to Echo Summit, which is about 7000 feet or so.  We stopped at a Costco just at the base of the hill to refuel....might as well since the gas is cheapest there.  From there to the lake, climbing the hill and driving at the limit with intelligence,  it got 22 mpg, with three folks and about 75 lbs of luggage.  That was about the same as the BMW gets....nice, but no big deal.  

(The AAA "How does this car rate" website says their '98-'05 (one of those) GS 300 got about 17 mpg in mixed driving....I KNOW I can beat that, without doing anything to the car.  I'm pretty sure this one was rated at 17 city, and 23 highway.)  

So, anyway....the next leg was the test...today's trip from Tahoe through Reno and Susanville up 395 and 299/139 to Klamath Falls and 140 to Medford.  That was 401.1 miles (7.5 hours of driving) from the Costco in Carson City to the one in Medford.  I kept the speed at the speed limit....it was 70 in Nevada, 65 in Ca., and 55 in Oregon.  We did have to stop three times for road construction...waiting in line for the pilot car to lead the oncoming traffic through a one-lane stretch (I shut it down each time), plus the obligatory tinkle stops, and we also had to drive through the downtown sections of Carson City, and also Klamath Falls.  The K Falls stretch was about 15 miles, and took the overall average down by a mpg or so, I'm sure.  I was watching the gas gauge 'not' fall down fast today like it used to do, and was looking for a good number.  I got it.

It got (as best as I can figure with the numbers I have....) 30.6159 mpg, using 13.101 gallons to go that distance.  Altitude had some input, too...the average altitude for this leg was over 4,000 feet.  We'll check what it gets below 500 MSL on the way home down I-5 on Friday.  

I think the engine is at the ideal rev range now, at 2500 +/- 50 at 65 mph.  Climbing up a steady gentle slope in Oregon at 55, where the revs were down to about 2150, the car could not maintain speed in 5th gear without complaining.  The cruise would instantly shift to 4th gear.  If I held it with my foot, it would decrease speed very (!) slowly, until the torque converter would unlock, allowing the revs to go up to 2400.  Then the car could accelerate...very slowly...but accelerate, at that road speed.  That tells me the torque is a bit low below 22-2300 RPM.  2500 looks like a good all around engine target speed.  (I was thinking of trying to gear it down to 2100 at 65...probably too slow.)

Now, if I apply the same logic to the SHO, and modify the front strut spring seats to allow 1 inch larger tires for cruising, I should be able to get 35 mpg at 70 mph at sea level.  That'll be fun to try!!   ;-)   It's got LOTS of torque, right?

George