the vectra is supposed to have a 0.29 CD (it formed the basis for the caliba and considdering it replaced the boxy ascona/cavalier mk2.. so at the time it really was a leap forward) but mine came with slightly wider tires and alloy wheels wich don't look that bad, but might still hurt the airflow.
this could add + 1 or 2 to the CD
than again i have the smallest engine available in this car and my top and bottom grill are partly blocked from the factory. i also removed the rear wiper as i rarely use it and the shape if the hatch is such the air could indeed follow it so the wiper seemed an aero killer.
i've read some honda crx's came with a rear wipers and some didn't, the ones without had a CD that was 0.01 lower so if you have a rear wiper it's only one screw to get rid of it, and you can keep it in the car along with the right spanner in case you want it back.... i can live with the attachement point for now...
so i guess the actuall CD will still be "around" 0.29 i hope the lower end.
the wheel dams i'm curently running are like the second picture
http://ecomodder.com/forum/showthrea...html#post51337
i'd like them to be a bit longer though.
i basically just used short wood screws to attach a bit of plastic to the plastic inner wheel well liner.
personally i think they're to small to reall help a lot, but as they don't hurt fe i'll leave them in place for now.
i'm also considdering rear ones but everythings metal there and it's a classic rust spot on these cars so i'm not going to drill.
ideally the undertray would have covered the sides but the sheet aluminum just wasn't big enough and i didn't want to get another one as i wans't sure it would work. still it seems to deliver an extra 1 a 2 mpg's on mostely off highway but with light traffic so while nothing huge with the curent fuel prices that's quite a nice improvement that paid for the sheet in no time
right now i'm toying around witht the idea if an active top grillblock, as the grills are already quite well designed i don't think it's wise to assume i can get away with a full permanent block all the time and blocking the top grill on a hot day with moderate driveing saw the temp climb quicky to the redline.
so i'd like something that opens when the fan comes on...