i have a Honda cr-v se 4wd 2011 i got the car with 7miles on. Now after 9 months i have 23,250miles on 95% of the driving is on a freeway, i drive about 90miles round trip. My question is… why driving on freeway is less stressful on the car then city driving. I live in Colorado so my commute to work is down the hill from Bailey to Littleton and up the hill to Bailey.
“What an engine likes to do is run at a constant speed.”–Tom and Ray Magliozzi
ShK
There is also this: very little shifting, braking or cornering on the freeway. In the city, the vehicle is constantly shifting, braking and turning corners not to mention potholes and curbs.
How many revs per mile does an engine turn at 70 mph in overdrive. How many revs per mile in 1st gear, 2d gear, 3d gear? And the engine is turning while stopped or inching along in a traffic jam.
What makes you think that highway miles are less stressful on an auto??
Of course it is, for the reasons above.
This type of driving is one of the things that makes cars like this go for 300k miles or more before it is used up. A human analogy might be the difference between an athlete jogging five miles (highway driving to a car) and doing five miles worth of shuttle runs (city driving to a car).
Remember that a car or truck is composed of many systems. To say that freeway speeds are easier on a car all the time is a mistake IMO. I can’t imagine driving I80 in the left 80 mph lane and hitting potholes is good for the suspension system. I can’t imagine a 4 wd truck spending it’s life on the freeway gets enough lubrication in the front differential then regularly driving at lower speeds in 4wd. I would never buy a used 4wd truck from an owner who bragged he never or seldom engaged 4wd.
We focus too much on what is good for the motor (change the oil at 2500 mile syndrome) and not the rest of the car. I believe that varied driving with am emphasis on steady speeds, is best. And no, unless you’re driving a Vette, that steady speed is not 80 mph. Todays transmissions get better lubrication when actually running through the gears, though not excessively so.
So highway speeds may be less stressful on the engine, but not necessarily on all the systems. OP’s motor, sure. But.
Without apropriate gearing, my old Sidekick would burn valves like cigarette butts driving all day at 70…and hitting a slight pothole at 80 can be more stressful then hitting a deeper one at 25. Consider wheel bearings, cooling system, tires, fuel delivery system and inner fender liners and body parts and paint that get pelted by debri at 70 mph. And if you don’t think a new paint job done right isn’t as expensive as many mechanical repairs…The age of a car is not measured in miles alone, but the actual time it’s in use and higher steady speeds do not necessarily always contribute to that outcome. A well cared for taxi can give you many more years of use then a highway cruiser.
“To say that freeway speeds are easier on a car all the time is a mistake IMO.”
Black is not always black and white is not always white. I’m just having a tough time coming up with examples of this, the way you have with your explanation.
Littlebean drives a 90 mile/day freeway commute and I was just trying to picture how a 90 mile / day stop & go trip in some kind of a Honda (sorrry, we don’t have any Hondas near here) on surface streets could possibly be easier on the vehicle.
Now it has become perfectly clear, I think, especially if you drive a car with cigarette butt valves, wimpy fender liners and wheel bearings that don’t like going straight.
CSA
Interesting thread. Lots of good info here. Allow me to add another line of reasoning, directed toward the engine itself.
Engines get their power by explodng gasoline in an enclosed chamber. As they do this, the explosions force the compression rings against the cylinder walls, as well as placing loads on the internal engine parts (lateral loads on the connecting rod bearings and wrist pins, lateral loads on the crank main bearings, etc etc). Piston rings are actually designed to push against the cylinder walls when top-loaded by combustion forces.
Accelerating a 2,000++ pound mass takes a lot more power than simply overcoming resistance to its inertial energy (keeping it at a constant speed).To get the added power needed to accelerate, more fuel needs to go into the cylinders for more powerful explosions. Many engines even pump the fuel in via turbochargers or superchargers. This much larger explosions create much higher loads on the aforementioned parts, as well as forcing the compression rings against the cylinder walls even tighter. That all manifests itself as accelerated wear.
In addition, the added forces to the valvetrain of the higher rpms when accelerating create added wear to the valvetrain parts, which are also subject to lateral forces (and rapid spring compression and decompression) as the engine accelerates.
An example of this in operation would be high performance engine and racing engines. They simply don’t last like street engines. They need to be constantly rebuilt. The reason is simply the added loads placed on the parts due to bigger explosions. It’s exactly the same principle, only brought to the extreme.
In summary, the higher loads you place on a given mechanical system is the faster it will wear.
One thing not mentioned yet is reduced rpm’s…thus fewer times a piston moves up and down in the cylinder walls (which causes wear) over the same miles when driven traffic. At 70mph my truck is running at just under 2k rpm’s. Driving in traffic…my rpm’s are higher for longer periods of time over the same distance traveled.
The proof is in the pudding! Ask any limousine company how many miles they get out of their brakes, transmissions, etc, and you will be astonished. I used to take a limousine to the airport 50 miles away. The company ran Cadillacs and Mercuries. They did the brakes at between 150,000 and 200,00 miles. They had never replaced a transmission.
The cars typically ran trouble-free for 400,000 to 500,000 miles, after which they sold them and replaced them with “fresh” models.
A couple of years ago while going on vacation…we took a limo to Logan airport…The Limo was basically a big VAN…It was one of the vans pictured at the website…
On the way down the driver was telling us that the van we were driving in was being replaced the coming Monday…It had almost 900,000 miles on it…original engine and tranny.
If you want to compare 90 miles of stop and go with 90 miles of interstate, you’re debating with yourself. My contention, if anyone bothered to read, is that varied speeds, with the majority at a steady rate and not necessarily 95% at freeway speeds is better. Highway speeds stresses systems of vehicles that are designed for other uses as well. Still, everyone gauges life expectancy in miles driven and not time used. The proof is in the pudding if you’re talking about limos and not puddle jumpers and purpose built vehicles.
You can’t get 65% of the guys on here to agree on anything. They are all “professional”.
None of us have disagreed here. We’ve simply all added our own additional reasons why highway mileage is easier on an engine than city miles. And some have pointed out that it has implications on other systems in the car as well.
I guess I’ll point out my reason why extended highway driving is easier on an engine than multiple hop, stop and go driving.
The engine and the metals used in it are designed to operate at certain temperatures.
With highway driving the metals will expand and pretty much stay there instead of going through repeated expanding and contracting cycles.
Many years ago Harley Davidson started cam grinding their pistons. This mean the pistons when cold are actually oval in shape and once up to operating temps they’re circular and fit the cylinder bore better.
(That’s omitting the sidewalk commando crowd putting on a profiling show for the public of course… ) 
Dagosa would have a point if we were talking about driving in Germany. Highway speeds in the US are so low that very few parts of the car are “stressed” excessively while going 70 mph in a straight line. Up that speed to 110 mph and, yes, the crankcase would be too small to keep the oil cool enough. That’s why police cars have extra cooling and other reinforced parts, and most German cars have larger oil sumps.
The Cannonball Baker Sea to Shining Sea Memorial Trophy Dash, the Canonball for short, even had a stock Cadillac V8 go virtually non-stop from NewYork to L.A. in less than 30 hours, averaging well over 100 mph where possible. It seem to have no ill effect on the drivetrain.
Since highway speeds are much higher in most countries, the average car can run vitually forever at 70 mph on a freeway.
I hear you Doc…but my 4 cylinder trucks, underpowered Sidekick and other purpose built vehicles with poor aerodynamics did much better at speeds much less then 70 mph. There are a plethora of modern day vehicles that do better at moderate, not high, freeway speeds. There are a lot of vehicles that don’t. My perspective is different and I can’t generalize.
Commuting between Bailey and Littleton is like track-driving the car…Hwy 285 becomes a fast-lane proving ground for Porsche’s and SUV’s dueling it out twice a day…Going home, the uphill grind adds long stretches of full throttle hill climbing and gear-changing…Come winter, add a set of studded winter tires and the games continue at somewhat higher slip angles…Reducing speed is out of the question…Damn, another $450 windshield…
This type of driving stresses every component of the car to the limit…Easier on the car than city driving? I don’t think so…
dagosa; the only car I ever drove that could not handle highway speeds of 60-70 mph was a 1959 Morris Minor, a British subcompact which the gas utility I worked for, erroneously bought to save money.
I burned the valves out on this little 1.2 liter long stroke engine in about 3 months. The company went back to standard 6 cylinder Chevies after that. They learned you can’t let the bean counters make these decisions without input from the maintenance department.
Even the 1948 stovebolt 6 Chevy I had handled normal 60-70 mph highway speeds well, but oil consumption increased at this speed.
I do, however, understand your point of view.