Originally Posted by YesMAN
You're correct, thanks. I think I was thinking of a next-size-up alloy being heavier, which is stating the obvious. Duh. This article on the C&D website was interesting. 16" alloys on a Golf were heavier than 15" steelies and caused the car to get slightly less mpg and was a little slower to 60. By this logic the Ti w/ 18's should be significantly slower than an S with 15's.
I still think the SFE's wheels and hubcaps are a marketing gimmick though. Why else would several other hybrids and cars in "eco" trim get multispoke alloys if they significantly degraded mpgs?
It doesn't have just weight to do with the package but the tire width and the rolling resistance of the tire itself. Wider tires and softer compounds for higher grip tend to be higher rolling resistance and faster wear. Most high FE packages have skinny litle hard tires for improved rolling resistance.
The reason I was asking the question on the 18" handling package was to see if those that were experiencing the lower FE were a majority of the Handling Package drivers or not. One interesting data point that was tossed on the table is that the 18's have a 2 psi higher air pressure spec. It may indeed prove to be that the rolling resistance is higher (hence better handling and grip) and the wider width may also be affecting aerodynamic drag. The 18" package may be resulting in a drop in FE but not necessarilly from wheel weight.