I'm planning on renting one of these 4x8' trailers from U-Haul: https://www.uhaul.com/Trailers/4x8-Cargo-Trailer-Rental/UV/

​​​​​​I Plan on towing it with some cargo (approx 500lbs) up the local mountain which is about 6k' elevation (orange county to Running Springs CA).

Has anyone experienced similar towing conditions and wondering how the cx9 handled it?

 

I doubt you'll have a problem. We towed our side-by-side ATV (1500 lbs) on an 800 lb trailer and the car handled it great. We weren't in the mountains but we were towing about 1000 lbs more than you would be. That little 4 cyl is strong. After towing our ATV I found out Mazda calls for trailer brakes for anything over 1000 lbs. I have considerable experience towing and in no way did the car feel unsafe. We only did it once but are considering doing it again because of gas prices; my Ram 3500 @10 mpg with $5.70/gal diesel makes for expensive traveling.

 

Unbraked trailer ATM limit in my market is 750kg / 1653lbs. Braked is 1800kg / 3968lbs

ATM = Total weight of trailer & contents.

 

Ask U-Haul for the weight of the empty trailer (tare weight) and the requirement in your state (California) for brakes on the trailer (I think it is 1500 pounds of trailer + load, but check). Surge brakes* on the trailer meet legal requirements and do not require additional equipment in the car. Your engine will run easier if you use the Sport mode when climbing hills**, and your brakes will run cooler if you downshift when descending steep hills.

*Surge brakes are a hydraulic brake master cylinder built into the hitch coupler on the trailer tongue. The hitch coupler floats forward and back and is spring loaded. When you slow the car the coupler slides back against the springs and applies the trailer's hydraulic brakes. When you pull ahead the coupler slides forward pushed by the springs and releases the trailer brakes.

**Let's say that a certain hill requires 100 horsepower from the engine to pull the total load of car & trailer up the hill at highway speed. The formula to calculate horsepower is torque x rpm divided by a constant (5252 in our Imperial system of measures). If the rpm is increased the torque is decreased to get the same 100 hp to climb that hill. Less torque developed is less strain on rotating parts of the engine. The Sport mode raises the rpm needed for each shift point.

 

Good information you found on the internet.... the only problem is that if you use that formula, you may find yourself in a world of hurt?
Mazda does not advertise or list true certified power ratings for any model gas engines from about 2002 and newer.
To be legal and able to advertise and or to place in vehicle specification "TRUE " power numbers they must meet the SAE J1349 certification.

Trust me in the last 10 years I get into long explanation to customers when I do a DYNO run and their pride and joy falls short of the auto makers claims output is suppose to be.
My own MAZDA was not exactly what the spec were claimed by MAZDA either. But at least I understood that.

 

The 1000 lb limit I referenced is from my owner's manual. It's a crock of $%^& that the same vehicle has different tow rating depending on where they are sold. Makes the whole thing seem subjective.

 

Fuel quality and access to some types of fuels, what the octane both RON and MON values and how they post the values in different countries all which effects the power output of an engine and the torque scale. Also the ECU mapping for EU vs US vehicles in many platforms are different that also effect the power.
The chassis is designed to carry any of the maximum specified weight as long as the power is there to support it.

 

Wanted to report back after the drive. I ended up getting the sightly larger 5x9 utility trailer and the CX-9 had zero issues pulling that thing up the mountain. It felt stable the entire way, very impressed. I did keep it right at 55mph on freeways, felt like it could definitely go faster but didn't want to test that theory.

 

Nice report.

As for 55 and towing a none commercial (large semi Truck & Trailer combo's specifically designed for faster towing speeds) or small vehicles the 55 if you look into why, it is mandated in most areas has to do with basic laws of physics. While many vehicles can pull faster speeds power to weight ratio's the control factor (aerodynamics and braking) diminishes exponentially as speed increases.
You sir are a wise individual and safe drive!!!