Acceleration mini-experiment

[kps]

(Cross-posted from http://www.fitfreak.net/forums/eco-f...ke-granny.html)

A. Slow acceleration. Shifts at 2500rpm.
B. Rapid acceleration. WOT in higher gears. Shifts around 2500 ? 3000 rpm in lower gears, and at 2500rpm in higher gears. Some wheelspin in 1st and/or 2nd gear due to the gravel road surface.
Note that cruising and deceleration were the same in both cases.

The car is a 2007 Fit LX with standard transmission.


The course is a 7.8km (approx. 5 mile) rural block chosen for minimal conflicting traffic. (Nevertheless, one run had to be aborted due to Mennonites.) I stop at 5 points -- each corner and one additional location -- and add one additional deceleration and re-acceleration.

1. IJKL 1.7km.
   IJ - Accelerate from standstill to 80km/h and hold.
   JK - Decelerate (in gear, no throttle).
   KL - Brake to a stop (clutch / neutral).
2. LMNP 1.4km.
   LM - Accelerate from standstill to 80km/h and hold.
   MN - Decelerate (in gear, no throttle).
   NP - Brake to a stop (clutch / neutral).
3. PQRS 0.9km.
   PQ - Accelerate from standstill to 70km/h and hold. (With gentle acceleration, there is not room to reach 80km/h.)
   QR - Decelerate (in gear, no throttle).
   RS - Brake to a stop (clutch / neutral).
4. STUV 1.6km.
   ST - Accelerate from standstill to 80km/h and hold.
   TU - Decelerate (in gear, no throttle).
   UV - Brake to a stop (clutch / neutral).
5. VWX 1.5km.
   VW - Accelerate from standstill to 80km/h and hold.
   WX - Decelerate (in gear, no throttle). Final speed is around 50km/h.
6. XYZI 0.7km.
   XY - Accelerate from 50km/h to 80km/h and hold.
   YZ - Decelerate (in gear, no throttle).
   ZI - Brake to a stop (clutch / neutral).

I made three runs using each method, alternating methods to try to avoid any changes due to other factors. The runs weren't perfect; in the B cases I sometimes overshot the target speed, and was unable to shift from 1st and 2nd quickly enough to shift at the target 2500rpm. On trials 3A and 3B other traffic slowed me briefly (part of segments LM and ST respectively).

In each case I had the car off briefly while recording information prior to the initial run or from the previous run. I turned the engine on, reset the Scangauge trip counter, and drove.


Run    Initial   Max   Avg   Max   Max    Fuel
      Air Water Water Speed Speed Engine  Eff .
      ?C   ?C    ?C   km/h  km/h   RPM   L/100km
1A    10   82    84    51    82    2844   6.6
1B    14   86    84    61    83    3559   6.3
2A    14   84    84    53    81    2710   6.6
2B    13   85    84    64    86    3308   6.5
3A    13   84    83    51    79    2738   6.5
3B    10   82    83    62    85    3513   6.2


Rapid acceleration to cruising speed is more fuel-efficient than slow acceleration. Presumably the greater fraction of the drive spent in high gear at cruising speed more than makes up for the hard acceleration.