So I drive a box, what can I do?

[dward1]

Hi all,
First post here, I've been a long time lurker though... I've drive a Toyota Sienna mini van(the parents) as a college car. I'm really sick of 20-24MPG and this car could really benefit from some aero mods. The car has a CD of .30 and I'm having trouble thinking up ways to improve on a steel box without heavy modification. The issue is my parents own it and though I do work as a mechanic and know what I'm doing it's not a good idea to mod other people's cars(especially your parents cars!) so, what ever I do has to be 100% removable and or out of sight out of mind.

I've been thinking about a full belly pan and some grill blocks but that's all I can come up with and I'm not sure how much under body work will improve the CD as the under body is basically flat already. Got any ideas, musings, suggestions??

Here's the box:

Thanks,
Derrick

[smokeyj]

Tire pressure to 2 lbs less than sidewall max
Adjust the driving nut (see tips section)
Weight reduction can't you remove for instance the rear seat?

[dward1]

SmokeyJ, I've got all the seats out and the spare tire and jack. Tires are already up to max(it's 5F here, i'm not worried about over expansion). I'm working on driving habits however I drive mostly highway with cruise on. I'm also quite frustrated with the shift points on this thing but that's another story...

This thing seems to hate fuel economy(It has this fast warm up circuit for instance that wastes monumental amounts of gas to keep engine temps up). This is why I'm at Aerodynamics. Short of a reflash of the whole powertrain this is about the only option I've got left.

[Frank Lee]

At least for winter put a grille block in there, at least a partial one. And I like engine blankets.

[dward1]

Great idea, I hadn't thought of that! An engine blanket would really help keep the engine out of that warm up circuit! I'm thinking that blocking the entire upper grill area would help, and if the engine can handle that seeing what I can get away with blocking on the lower one. Also, while i'm at it blocking those faux brake ducts too.

[cfg83]

dward1 -

What Frank said. You can cover the upper grill and be "aggressive" with the lower grill too. I am thinking that you could probably get away with just the center two slats open for winter :



Try tape at first and monitor coolant temps. If it's too hot, peel off successive layers of (vertically placed) tape, and repeat the test until you reach temps that are comfortable for you.

Does your Sienna have a roof rack? It looks like a stock photo, is why I asked. Would removing that be too much for the parental units?

CarloSW2

[Frank Lee]

It's winter in Sconnie, might have a tough time with tape.

I use cardboard, it can be cut/folded as needed.

[dward1]

It does have a roof rack, I just checked and its only 16 torx's screws. Thats definitely coming off!

[dward1]

Good point Frank. I think zip ties and a cheap sheet of plastic might be in order. It looks like a front under tray could use a bunch of fastner holes all ready there so that's on the list too.

[MadisonMPG]

After reading the other replies, my only suggestion is...slow down if you can.