Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Effect of wet roads on efficiency: estimated 14.5% MPG drop

Piwoslaw · 10-15-2009, 01:15 AM

I've noticed a slight drop in FE (10%) when it's raining. This may be b/c then I drive in gear a little more often, less coasting, especially in traffic. But then I drove slower, and use even more engine braking.

I've also been thinking that effect of raindrops on the car. When a car is going at a constant speed and is hitting drops of rain (whose velocity vector is usually orthogonal to the car's direction of movement - I'm assuming no wind), then each of those drops gets accelerated to the car's speed. When you add up the total weight of all drops over a certain distance or time duration, it's like accelerating a large mass of water.

10-15-2009, 01:15 AM	#19 (permalink)
Piwoslaw aero guerrilla Join Date: Oct 2008 Location: Warsaw, Poland Posts: 3,703 Svietlana II - '13 Peugeot 308SW e-HDI 6sp 90 day: 58.1 mpg (US) Thanks: 1,278 Thanked 731 Times in 464 Posts	I've noticed a slight drop in FE (10%) when it's raining. This may be b/c then I drive in gear a little more often, less coasting, especially in traffic. But then I drove slower, and use even more engine braking. I've also been thinking that effect of raindrops on the car. When a car is going at a constant speed and is hitting drops of rain (whose velocity vector is usually orthogonal to the car's direction of movement - I'm assuming no wind), then each of those drops gets accelerated to the car's speed. When you add up the total weight of all drops over a certain distance or time duration, it's like accelerating a large mass of water. __________________ e·co·mod·ding: the art of turning vehicles into what they should be What matters is where you're going, not how fast. "... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell [Old] Piwoslaw's Peugeot 307sw modding thread