1300 mile trip results:
46 MPG!
For analysis, I note that this car looks very similar to the 1986-1992 VW Jetta in the
CdA list. It also has similar outside dimension specs. I don't have specific CdA data for the Corolla.
Analysis:
Assumptions:
- 65 MPH (trip time minus approximate stops / total distance)
- 59°F average outside temperature
- A=21.8ft^2 (like the Jetta)
- Gross weight 2300 lbs (including me and my tools)
- Crr >= 0.008 (generic tires at 44 PSI)
- engine efficiency <= 25%
Result:
Cd <= 0.28 or >22% reduction from stock 0.36 (Jetta).
Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com (Why I used trip data with the calculator: long haul results are dominated by CdA, with very little city driving, etc. The primary uncertainty is wind speed, followed by engine efficiency and Crr. My impression is the wind was neutral overall on this ride. It tends to be so on a round trip.)
Not bad for a >23 year old car with just a handful of mods. (EDIT: maybe. I'm pretty sure I'm at least 10% ahead of stock. Really it's tough to know since I don't have a baseline for this type of trip.)
Mod list for this trip:- Blocked upper grill
- Air dam with cooling inlet
- Slick wheels
- Rear wheel skirts
- P&G (but not much EOC)*
- (Earlier I had a gap filler right above the bumper. I had to take it off within the first 100 miles for the little bit of extra cooling it offered. It's a big gap, basically a third grill. When I finish the ducting I should be able to close it off.)
* I have never done a long trip with high speed P&G before, but now I love it. It solves 2 problems: a) throttle loss, especially in this car with its not-so-tall gearing, b) prevents fatigue of my heel, especially in this car having no cruise control. I believe that EOC is not so beneficial with the carburetor, since it takes a couple seconds for the engine to die and I expect it consumes fuel while it tumbles. Bump start is also a bit slow and consumes more energy than in my other car. If the glide is shorter than about 10 seconds I leave it on.
Other thoughts:- It has really bad groove wander. The shimmy is not as pronounced but still present, although it depends on how smooth the pavement is.
- After the first 630 mile leg, I ran a 6 mile errand and the passenger drive axle fell out enough to leak transmission oil and made a big mess. I put in a refurbished axle (by chance this happened just outside my dad's garage) - and found the old axle was missing the retaining ring. Weird. Bizarre even.
- I tried to make this a reliable car and feel like I got burned. Maybe it was a fluke... like the two tire rod ends... and the muffler... and the clutch... and the groove wander... and the shimmy...
