The boat tail is complete, and I just took it for a 40 km drive:
Above: failed attempt to get some quick tuft test results. These pics are screen caps from my crummy 2 mp digicam movie that isn't quite up to the task of resolving the tufts - there really are a bunch of them on the back of the car in those pics! (I'm still planning to do the webcam-on-the-car trick that I know will work.)
The drive: 40 km round trip, next to no wind, about 7 C.
Observations:
- Once the car warmed up, it was pretty clear this is one of those rare mods that doesn't need A-B-A testing with a ScanGauge to really know there's an improvement.
- I can go faster than I used to at a given MPG point. I used to have a saying: "70 at 70" - a rough guideline that meant that I could drive with load on roughly level ground and sustain about 70 mpg (US) at around 70 km/h indicated (faster actual speed, since my speedo under reports by 6%). But on this drive, once the car warmed up, I was able to hold that 70 mpg at around 80 km/h (50 mph) indicated (faster actual speed).
- Based on that, a 10% MPG improvement at highway speeds doesn't seem out of the question.
- on a downhill I regularly drive I had to back WAAAY off the throttle compared to before to keep from accelerating past the speed limit
- seemed to be able to hold 5th gear longer on a couple up uphills. I love being able to climb mild grades @ 50+ mpg!
- the boat tail literally stops traffic. A guy actually came to a halt in his Chevy Avalanche in the middle of a turn in an intersection to gape - blocking through traffic from two directions.
- It's off kilter! Only noticed this once I got it out of the garage and could stand well back and look at it from behind: the tip of the boat tail isn't inline with the centerline of the car - offset to the passenger side about 3 inches. So much for eyeballing it inside a cramped garage! Should have used the tape measure again after setting up the bulkheads, before starting to put the skin on.
- It's strong enough. I can grab the tip of the boat tail and shake the entire car side to side and up & down, with very little movement in the tail itself. Yay for "hurricane tape".