Discussions of the cruise control variation on hills has been documented on this site previously. After experiencing it for the first time this last weekend, I contacted my local dealer. They checked with Toyota support who returned the reply that all parameters are working as designed and no changes will be made. At the dealers recommendation, I called Toyota Customer Relations at 1-800-331-4331 and filed a complaint # 200701250758. They took the info and said it will go to executive management plus engineering. It was also stated that I will not hear back from Toyota regarding.

I then filed a complaint with the NHTSA ( http://www.nhtsa.dot.gov/ ) complaint # 10182654. I believe at 70mph that the 7mph swing in speed is enough to cause safety issues. Here is the text from the NHTSA complaint:

"Cruise Control varies speed by 7 miles per hour hour when engaged during non flat terrain causing a safety issue with cars following. When on flat terrain the cruise control maintains its target speed within +- 1mph with no problems. The safety issues occurs when the vehicle encounters rolling hills, the cruise control will allow the speed to decrease by as much as 5 miles per hour while descending down the hill, then as it begins to climb will aggressively accelerate to 2 miles per hour over the target speed. When the road flattens out again it will maintain the original target speed. At highway speeds, 70mph, this causes safety issues especially when traffic conditions are moderate to heavy in that traffic follow will not have any indication that the speed is slow by 5mph. This in turn will cause a hazardous situation where a collision could occur. This has been reported to the local Toyota dealer and Toyota support responded that all is working within parameters and no adjusts are planned. Case # 200701250758 has been opened with Toyota Customer Relations with no promise of action."

What I didn't state was the potential for "road rage". Imagine heavy traffic and someone getting mad at your loved one because they are swinging their speed by 7mph constantly (given back to back hills like we have on I-35 between Dallas and Austin).

You as TCH owners have several choices:

1. you agree and do nothing
2. you agree and file a similar complaint with Toyota
3. you agree and file a similar complaint with NHTSA
4. you could care less and do nothing
5. you completely disagree with my actions and slam me

Big Al
Georgetown, TX

I agree, but think if the traffic is heavy enough that a collision is possible, you should not be using cruise control.

^ I'd have to agree with ag4ever

07 TCH - slightly modified

I too agree and when the traffic was that heavy it was turned off. The problem with some Texas drivers are they often tailgate even when traffic is not heavy, like the back end of the car in front is a magnet drawing them closer.

Again, I'm not defending any of my actions just posting my frustration and the action I personally took.

Big Al
Georgetown, TX

I understand your frustration and it does appear that a 5mph drop in speed is a little more than I would expect. Kudos to you for complaining to Toyota.

However if this is the case there is nothing stopping you from putting your foot on the gas and accelerating to the desired speed on those downhills.

Cheers
Steve

I'ld have to agree with ag4ever too. Cruise control doesn't give the driver an excuse to not pay attention to the surrounding cars. They should be ready to override for whatever reason.

I also agree, that cruise control is there to assist the driver, not replace him and ultimately it is the driver's responsibility to keep the proper speed. I've also never seen speed dropping down the hill, in my car it's just the opposite, the car begins to free roll and overspeeds down the hill, but I don't think me blaming the cruise control would fly with the cops and judge so I watch my speed even with cruise control. As far as road rage, some people will get piss that you drive too slow, others that you're going too fast, so what. As far as tailgating I saw a moron tailgating a bus (actually as a matter of fact it was in Texas when I drove cross country from NY to NV) right next to me, in a pick up truck. You can figure the rest: Bus hits the breaks , pick up truck hits the breaks and locks up rear , then it goes sideways into a ditch and flips over. I was extremely lucky he didn't hit me since I was right next to him and once the rear locked up he had no control over his car whatsoever. Hopefully the driver wasn't hurt and learned his lesson. I don't think people should slam you, you did what you feel was right, others don't have to agree 100%, that's life.

I also agree, that cruise control is there to assist the driver, not replace him and ultimately it is the driver responsibility to keep the proper speed. I've also never seen speed dropping down the hill, in my car it's just the opposite, the car begins to free roll and overspeeds down the hill, but I don't think me blaming the cruise control would fly with the cops and judge so I watch my speed even with cruise control. As far as road rage, some people will get piss that you drive too slow, others that you're going too fast, so what. As far as tailgating I saw a moron tailgating a bus (actually as a matter of fact it was in Texas when I drove cross country from NY to NV) right next to me, in a pick up truck. You can figure the rest: Bus hits the breaks , pick up truck hits the breaks and locks up rear , then it goes sideways into a ditch and flips over. I was extremely lucky he didn't hit me since I was right next to him and once the rear locked up he had no control over his car whatsoever. Hopefully the driver wasn't hurt and learned his lesson. I don't think people should slam you, you did what you feel was right, others don't have to agree 100%, that's life.

If traffic is heavy enough to be a safety issue then cruise control should be disengaged. Standard operating procedure IMO.
Unlike my '04 Prius my TCH speeds up on downhills. A lot.

Hi Big Al. Don't let anyone get you down, you are not the only one to have this problem. I've experienced it as well. And yes I only use cc when conditions are safe.... Geez give the guy a break. he noticed a problem and posted it here to share - not to be flamed. nobody will ever agree 100% but jumping to conclusions... man... and when cars are traveling at highways speeds things tend to happen very fast regardless of how many cars on are on the road with you.

cc is a convenience and not a necessity as pointed out. but as I experienced when you begin up a very slight grade and your speed drops by over 5 miles per hour. well, even the car following you at a safe distance behind starts to close in very fast - at those speeds. fortunately in my case all parties were paying attention (I hit the gas, and the car behind was able to change lanes) and nothing came of it. Since my first and only time using cc I've simply chose not to use it again.

This does seem to be a problem and thanks for sharing your experience.