Me thinks most cars these days have power-assisted brakes…Not a brake engineer, but don’t they get they vacuum power from the engine? If an engine is at WOT, vacuum would drop after a few pumps, no?
Correct.. though some vehicles have hydroboost — mostly trucks.
The vehicle will still stop in the same distance without the power assist.. it just takes more pedal pressure. The limit on braking depends upon the tires static and kinetic coefficient of friction with the road and thermal reserve in the brakes. The power assist just makes it easier to push the brake pedal.
However, the thing I did notice is the design of the shift gate pattern is horrible from a usability perspective
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It’s especially confusing if you were in tiptronics(or whatever lexus calls it) mode (furtherest to the left) and are trying to shift back out.
It didn’t look too bad. Looking at the gate, the patterns I would have tried starting from the full left position would have been straight up (checking if the straight up past upshift toggle would lead to neutral – which is not likely), back to center-left, move lever right then up.. pause and then right again. I suspect one of those two last positions is neutral. I haven’t driving this Lexus.. but surmising as an ‘uninitiated’..
As the car surged forward I hit the brakes with my left foot hard at 80 mph, right foot still planted on the floorboard. The brakes hauled the car down, was it smooth, no, the car was shaking like the rotors were warped but I expect it was the anti-lock system kicking in. As I slowed enough to have ditched the car, put it against the rail, etc. Appx 20 mph and the brakes were still good….
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This time I had about 1/3 the braking force as before and the car would not stop. It did slow but not easily and not nearly enough. I let off the brake pedal and ran it back up to 80. I immediately hit the brakes hard again. This time…..I had essentially no brakes. I stood on em. They had faded. My conclusion. On this car you have one chance to stop with the brakes with the engine at WOT.
This is essentially what I mentioned earlier with the braking. If the car is trying to do run-away acceleration.. don’t try to use the brakes to keep the speed down and legal. Stop the car. Very few cars made these days can handle repeat stops under those conditions, and riding the brakes will just heat them up.
About the start/stop button. How do you normally stop the engine when you park it.. hold the button down for 3 seconds?? If that is the case, it is no different than when car is in motion. If it is different, this is the only one I could see that would be a problem for someone unfamiliar with the car.
All this also indicates that most of what the piggs brought up about the vehicle, would have worked.. with the only potential wildcard being the stop-start if it was different between at rest and in motion (ie. immediate shutdown when at rest and 3 sec delay when in motion)
