Do cars drive more efficiently in the wet?

Question

they don't need to overcome so much friction from the road.

Answer 1

They have less control because of "hydroplaning".

Answer 2

Less friction causes the tires to spin and be less efficient. Also it's harder to stop.

Answer 3

The only thing keeping you from sliding off the road is the friction between the tires and roadway.  Lowered friction means that energy created by the motor is lost in slippage.  This is a loss of efficiency.  Ever try to take off quickly in heavy rain?  Your tires probably spin a little, which is wasted energy.

Rolling resistance is a measure of the friction created between the tire and the road surface.  Small, narrow tires with hard compounds have low rolling resistance, while large, wide tires with soft compounds have higher rolling resistance.  Tire manufacturers spend lots of time and money striking a balance between wet and dry performance.

If the air is more dense, it takes more energy to push it out of the way.  Water is more dense than air, it's far easier to drive an object through air than through water.

Increased moisture in the air inhibits the stoichiometric balance in the combustion chamber (cylinder).  Today's diagnostic on board computers can adjust fuel ratios (stoichiometry) to compensate for this, effectively eliminating the lost efficiency within the engine.  The tires still have to push through the water, and wider tires have to push more water farther from the centerline of the tire.

No, cars are not more efficient in wet conditions.

Answer 4

nope. more resistance from rain

Answer 5

Yes and no

Cars engines operate more efficiently because the air is cooler and more dense, therefore improving ignition.

They drive less efficiently because water on the ground is more dense than air. Like a boat, the tires have to plow thru the water.

Thanks Bill, I was thinking that but couldn't find the words.

Answer 6

Yeah, but the less friction means less control. Plus they have to push the water on the road out of the way so it's probably a push.

Answer 7

No, they definitely do not.

You might be confusing "traction" with "rolling resistance".   One is not the other.  

In the rain, traction goes down a lot, and rolling resistance goes up because your tires must also push through rain on the road.