Grill Block Poll.
 

I have a grill block in my VX, nearly flush with the rest of the bumper, left an area about 3" by 4" open right in front of the radiator, simaler to the OEM grill block opening, I also closed over the fog lamp openings, I didn't notice any change, so I'm wondering if I'm alone in this.

I did my grille block at the same time that I was learning all the new hypermiling techniques.

While I certainly saw some significant gains during that time period (from 40mpg up to 48mpg) I can't attribute my gains to the grille block.

Just put a lower grill block on my BMW 325is this morning, and drove the car about 130 miles, mostly highway cruising at 80 mph, but also in some freeway commuter traffic and some in town.

So, results are highly subjective, at best preliminary, and based on the on-board fuel computer, which has been reliable in the past. That said, at highway cruise speed, the OBC indicated a mile or two better mileage over the same stretch of highway that I've monitored many times before, and the car "seemed" a bit smoother and quieter, presumably due to less turbulence. This is not a proper test, only a preliminary impression, so take it as such.

I'm still making assessments, But I put a GOOD grille block on, the bottom one didn't hold up well so I just left the top. It runs hotter, heats up faster, and seems to run smoother.

I don't know, but judging by how many miles I've driven and the fuel gauge position, I'd say that I'm getting between 22-25mpg's this tank. which is better than ever. More tanks will have to confirm, but since I'm on spring break and not driving, I'll say that that'll be a few more weeks :D

My car showed higher speeds (~3mph) during NC coast on hills, with grill block and passenger mirror delete. With all gaps taped or weather-stripped on the front end, and the other grill opening partially blocked, I now coast at 70mph where I used to get up to 65.

Faster warm up....

If I engine brake to a stop light - my coolant temp drops 20-30+ degrees otherwise...

I'm a beleiver
 

I installed a grill block on the Geo in mid Feb.
My mileage has improved, noticeably.
42 mpg when filled in Feb.
48 mpg when filled in Mar.
Halfway though this tank I removed the right side mirror and added one of the wide angle interior mirrors.
I am sure this helped but this was also only the last half of the tank.
After covering the grill, I was able to coast longer on several of my regular stretches.
There is a point in my after work drive where I cut the power and EOC till my exit.
I have been moving my begin marker further back since installing the block.
My best EOC before block was ~ .7 mile.
Now I'm up to ~ .9 mile
As for noise, the Geo is very loud inside and I can't tell a difference.
However there used to be a rattle/hum from the front left @ 55 mph, I don't hear that anymore. May be some piece of deflector material behind the grill is loose that no longer gets the wind.
So in response,
Emphatically,
Yes.
So much so that I purchased the VW grill block for my Daughters Jetta.
Now I just have to put it on.
S.

I installed the Matrix's grill block this fall as it was getting colder out. The mileage was plumeting and the next tank actually stayed the same or was slightly better and temps were continuing to go down. Faster warm up was also a big deal as the wifey likes comfort.

I put in an above-bumper, behind-the-grill block and immediately noticed 3 differences:
> The engine warms up about 30% faster
> The car is more stable (less nervous, slightly quieter) at highway speeds
> Coasting distance is noticeably longer even at moderate speeds (60 km/h).
So it works!

I did an A-B-C (admittedly not ideal) back-to-back test on a fully warmed up car and noticed an immediate improvement as soon as the block was installed:

http://metrompg.com/posts/photos/ACFBE8B.gif

http://metrompg.com/posts/grille-blocking-part-2.htm