Mud Flaps--Initial Impressions

[efusco]

I installed my mud flaps, purchased from ToyotaTown (a PriusChat Sponsorer) 2 days ago and already am able to give some opinions/observations that I think might interest others considering buying these.

Appearance: They look nice, quite OEM, non-intrusive and don't signficiantly break up the natural lines. It would be nice if they were smooth/convex on both sides, but it's not a big issue and the cost differential is probably signficant.

Effectiveness: Not bad. They definately reduce/eliminate the bad spray that occurs right behind the wheel well area. I'd hoped they would stop the spray from hitting the rear-view mirrors, but they don't, that comes off much higher than the mud guards go.

Affect on Mileage: Unfortunately I think this is going to be more significant that was previously reported. I don't have enough miles to say exactly what the percentage or absolute mileage impact will be, but I have seen a DEFINATE downturn in my mileage over the past 2 days that is not attributable to any change in weather, driving habits, route, weight carried or any other changes in the car. At 370 miles into the tank I showed a 58.3mpg average for the tank--I had not dipped below 58.0 at any time during that period. Since adding the mud flaps I've seen a steady slow decline in the displayed average to 57.7 at 425 miles. So, over a 55 mile stretch of driving my mileage has been reduced by over 1/2 mpg. Over a tank of gas I have to think it's going to be even more.

Conclusions: Draw your own, and at $45 for a set of these plus an hour of your time to install them it's worth buying them and making up your own mind.

For me, I'm leaving them on, at least for now. If I find that I can't get my mileage up to where I think I can/should be and I'm not satisfied with the job they're doing I'll take them back off of the car (should be very easy and take maybe 15 min to do that). I have to say that I'm concerned about the reduced gas mileage, esp. after becoming so optimistic over the past 1000 miles of driving that I could consistantly get in the 55-58mpg range. I don't mean to discourage anyone else from getting the flaps, their benefits probably outweigh the loss of performance, but I wanted to make folks aware of that impact.

[DonDNH]

What with all the gee whiz bang things that Toyota did build into the car, a set of mud flaps that extend and retract into the fender well at the touch of a button on the dash would have been a nice addition.

[eak354]

i like em. i didnt notice much dip in my mpg since i was averaging around 44mpg to start with (mostly city driving). after a downpour, i washed my car, and alas! none of the usual mud, grime and tar i'd get without the mud flaps! 8) well worth it!

[twindad]

Touch of a button? How primitive! I would expect it to measure flying mud in real time, compensate for wind direction & speed, & deploy automatically!

[htmlspinnr]

And for those of us who are a bit more feature conservative - it's just one more thing to break down the road :-P

[mikepaul]

Originally posted by eak354
i like em. i didnt notice much dip in my mpg since i was averaging around 44mpg to start with (mostly city driving).  after a downpour, i washed my car, and alas! none of the usual mud, grime and tar i'd get without the mud flaps!  8)  well worth it!

Yea, the only time I see 50MPG+ is on an extended trip. The average right now is hovering at 47.4MPG, so if it drops to 46.9MPG after I install the soon-to-be-delivered flaps, I won't cry...

[bookrats]

Originally posted by htmlspinnr
And for those of us who are a bit more feature conservative - it's just one more thing to break down the road :-P

Now there's a man who's had lots of experience with technology! You haven't had to write Windows applications, have you?

[Bill60546]

My silver 9 looks just fine with the mudflaps. And anything that keeps road salt, gravel, rocks, etc. off the car is well worth $45. Afterall, a clean rust free Prius is a happy Prius! :multi:

[efusco]

Just to add a little update, the mileage hit is real and it's going to be pretty significant. I've dropped from 58.3mpg @ 360miles in the tank to 57.4 at 480 miles into the tank...and I've been driving very carefully to keep it that high!

Again, I haven't decided if that will be important enought to me to take the flaps off yet, I'll probably give it a couple more tanks before I do decide, but if one of your 'big things' is squeezing every possible mile you can out of a gallon of gas then be aware that this will affect that mileage. And that makes sense, let's face it, if those little grooves in the roof and the rings on the wheels affect aerodynamics then adding 4 1 square foot air scoops to the car will definately have an impact.

FWIW on a more techy note, I've found it much harder to 'dead band' with the flaps, I can't get into a no-arrows coast and sustain it nearly as long as I could before. The increased drag forces me to engage the ICE again much sooner than I had to before.

[Bill60546]

Evan:
Based on your figures, thats a 1.7% decrease in MPG or 98.3% of non-impact. I wouldnt exactly refer to it as "real and significant". Please think about the total cost of ownership (TCO) vs MPG. We may pay 1.7% more in gas costs but save in body repairs, rust prevention, improved resale value, reduced frequency in car washes, etc. That adds up too.
At 12K miles per year, $1.85/gallon, 50MPG average, (remember I like good old fashioned round figures) that adds up to roughly $7.54 in incremental annualized gas costs; proverbial peanuts. A single car wash here costs $13. Over an ownership period of say 5 years thats about $35 in gas costs. Now the real question; do you believe that at the end of that 5 year period you will spend atleast $35 or more fixing rust spots, tar removal, etc. Mud flaps are a no-brainer. (But then, I've been accused of that before! :mrgreen: )
The real money saver for body work will be the body side moldings. Am still waiting for Steve to confirm cost and availability.