March 3, 2024 - Coming down from the top of Haleakala - in any car - can be a dangerous proposition. If you misuse the brakes, they can fade, fail, or catch fire - leading to an accident. 

WHAT CAN HAPPEN IF YOU OVERUSE THE BRAKES

Over-using the brakes causes the brakes to overheat and this can lead to a number of very real problems.
1. The brakes pads exceed their operating temperature limit and deliver less stopping power, because they become slippery and cannot grab. This means no matter how hard you press the brake pedal, this does not slow down the vehicle.
2. The brake fluid boils, leading to a loss of brake pedal function. Like the brake pad fade, this means pressing the brake pedal does not slow down the car.
3, Components of the brake system can catch fire. This can happen in extreme cases and it's very dangerous if it does, because it can lead to a larger vehicle fire.
4. Brake shudder. This is a result of milder overheating.. After the brakes are over-used, the driver will experience shaking in the steering wheel while applying the brakes. This is not dangerous, more of an annoyance, and certainly does NOT inspire confidence for the next customer renting the car, but it is a permanent lasting fault that can be repaired only by replacing the brake pads and rotors - which is something that we end up doing regularly, on brake systems that were perfectly fine until someone drove them down Haleakala.
5. Brake pad glazing. Just as it sounds, the surface of the brake pads turns to a "glass" because of high temperature. The brakes still deliver some stopping power, but less than expected, and require more pedal pressure for the same stopping power. The brakes may also make unexpected scraping or grinding noises when being applied. Like shudder, this presents less immediate danger, but it is also a lasting fault that requires replacing the brake components.

WHY ARE THESE ISSUES MORE LIKELY WHEN DRIVING DOWN HALEAKALA.
Crater Rd, aka State Hwy 378, descends from the Haleaka Summit to Kula Town. It drops 6,500 feet in just 5 miles as the crow flies. That's more than 1,200 feet of elevation drop per mile - making it one of the biggest sustained drops in the entire US. 

To be fair, the road does not come straight down from 10,000 feet. It winds through twists and turns, making the Point-to-Point (P2P) distance different from the Driven Distance (DD). 

Let's compare P2P and DD for the three main segments of the road from the summit to sea-level. 

First let's define the main points along the way. 

Point A. Hana Highway State Hwy 36) and Haleakala Hwy (State Hwy 37). Sea-level
Point B. Haleakala Hwy (State Hwy 37) and State Hwy 377. Elevation 1,750ft.
Point C. State Hwy 377 and Crater Rd (State Hwy 378). Elevation 3,450ft.
Point D. Haleakala Summit. Elevation 10,000ft. 

Now for elevation changes, driving distances (DD), and grades, on each of the three segments A-B, B-C, and C-D. 

.........Elevation................................Grade
.........Change(ft).......DD (mi)..........(ft/mi)
A-B..........1,750................7.7...;;;;;.. ....227
B-C..........1,700................5.8...............293
C-D..........6,550..............20.7...............316

Clearly things start to get steep when you turn off from Hwy 37 onto Hwy 377, and steeper yet after the turn-off from Hwy 377 to Hwy 378 (Crater Rd). On this final segment the road drops 316 feet in every mile of driven distance, which is 5,280 feet per mile. That's an average grade of 5.98%, which is just a hair under 6%, which is the steepest grade you are likely to encounter on any public roadway anywhere - and you know that some sections are even steeper than the average! 

HOW TO DRIVE DOWN SAFELY FROM HALEAKALA SUMMIT

With these kinds of grades, to get down safely, you cannot rely on just the brakes to keep your vehicle speed under control. This would definitely cause the brakes to overheat and potentially lead to disaster. 

Along the way, you will see many signs enjoining you to use low gear on your vehicle. We know from experience talking to many customers that either they do not register these signs, or they do see them and believe that they do not apply to them, because the vehicle pictured in the sign is a truck. 

DO "USE LOW GEAR" SIGNS APPLY ONLY TO TRUCKS?
No. Using low gear on the way down steep roads applies to all vehicles, not just trucks. 

HOW DO YOU KNOW WHEN TO USE LOW GEAR.
If your foot is on the brake for more than half the time, for example you're braking for two seconds every four seconds, or braking for three seconds every six seconds, and so on, and this lasts for more than one minute, then you are over-using the brakes, and you should use low gear. 

HOW TO USE LOW GEAR.
What you have to do in order to get down safely is to use "engine braking" by engaging a lower gear on their transmission. 

We also know, from talking to many customers, all of whom mistakenly believe that after x years of driving, they know how to drive a car, that most of them haven't the faintest clue how to engage a lower gear, what a lower gear is for, what engine braking is. Or the mistakenly believe that this cannot be done on a car with an automatic transmission. Or some other cockamanie belief about driving featured in their overall cockamanie belief system that they live their life by. 

If only they had spent a few minutes leafing through the owner's manual of any of the cars they've owned in their lifetime, they would have seen the subject of gear selection and engine braking prominently featured - because it is universally considered as crucial for operating a vehicle safely. This is, of course, assuming that they can read. 

Ok you don't even really have to be able to read, you can just look at the pictures. For your convenience, we are posting pictures of the most popular gear selection lever types from cars of the last few decades. Most cars on the road today - regardless of brand - have something that resembles one of these. 

To get down safely on a long steep hill, like Haleakala's Crater Road, you use the gear selection lever in your car to shift into a lower gear. It's the same lever that you use to get out of Park and into Reverse or Drive. You can select a lower gear while the car is moving. When you select the correct gear for the steepness of the hill, the car's speed will stay at a reasonable limit, without any use of the brake whatsoever. 

WHAT TO DO IF YOU EXPERIENCE A LOSS OF BRAKING POWER DUE TO OVERUSE OR OVERHEATING

If you sense that the brakes are not effectively slowing the car, then immediately take these measures, for your own safety:
1. Use the emergency brake
2. Shift to low gear
3. Pull over and wait for the brakes to cool down.

WHAT WE DO TO PREVENT BRAKE FADE IN OUR VEHICLES

1. We use ceramic brake materials that are more heat resistant (and cost more).
2. We use DOT4 brake fluid that has a higher boiling point.
3. We regularly perform brake system bleeding to ensure that the brake fluid and its performance are not degraded. 

Enough about the brakes. Back to our weekly survey of rental car prices in Maui. For a one week rental beginning on Monday, 3/4/24, these are the lowest advertised rates:
Off-airport (with shuttle) $219.88
Airport rentacar center $322.91
Source: Rentalcars.com