it really doesn't matter for me, but is it more fuel efficient to drive with the top up or down? it's not going to change my thought to put the top up or down often.

 

the recently decreased rating is due to a revised fuel economy rating system, not a decrease in fuel economy--just like the decrease in horsepower.

increasing tire pressure above spec will decrease rolling resistance, but it also decreases the contact patch and has a negative effect on cornering. your overinflated tire starts to look
like this: (===)
instead of this: |===|
or underinflated: )===( <===due to sidewall rigidity i think, but that's the wear pattern anyway

if you JUST installed TP/I/H/E, a large part of fuel economy improvements are because the outside temperatures are warming up, and cars will get better fuel economy in the summer than in the winter. they may help anyways--i don't know.

and i get 22mpg combined on average, but less lately

 

I just checked my mileage driving the car like an average small car with 50% highway and 50% city, I got 28 mpg. Driving it hard would probably get significantly less.

 

what tire pressure should i put should i set if im running a 255/40 17

 

I get much worse mileage top down.

2-3 mpg

Thats significant when you're in the 20's

 

Not exactly relevant to this thread, but I average about 18-19mpg with a turbo setup running 625cc injectors. This includes a healthy mix of highway, in-town, and a fair share of WOT pulls. On a recent trip to CT I got 25mpg. Worst I've seen is <10 when I first got the car back from the shop, lol. Before going FI was seeing 23/28 mpg.

 

i got about 10 on the track, well maybe less wasn't really keeping up.

 

I get around 25.5 mpg zipping around (half highway+half city). oh yeah... and I am all stock except for a CAI.

 

same here. best ever was 24mpg all highway.

 

[QUOTE=Clemsons2k,May 12 2008, 04:48 AM]