
Driving Dynamics Lab; experiment #1
Tuesday, June 19th, 2007
OK dammit, it’s been long enough, the Fit is here, the Fit is fully broken in, and I’ve done enough laps around Ohio now to have some sense of what it is actually trying to accomplish while I’m driving it.Â
 First, some particulars on me. I don’t race, I stopped street racing years ago, and most of the time i am usually trying to eke out maximum MPG to really piss off those fools who shell out thousands more on hybrids and can’t match the mileage numbers I get with my otherwise ordinary car. [I get between 39-43 MPG in mixed city/highway, by the way. EPA est. for the Fit is 31/38 city/highway.] But at the same time I do enjoy finding the apex, and driving in a spirited fashion. G forces are fun.Â
 Now, we can’t go for a drive unless the car is prepped properly. Mechanically, the car is still completely stock, right down to the 175/65-14 all season Dunlops. They are quiet, and ride pretty well, but I keep looking at Tire Rack ads for acceptable plus zero sizes. Stock pressures are 32 psi front and rear, but mex. press. on the tires themselves is a healthy 44 psi, so for the moment anyway, I’ve set the pressure at 40 psi front and rear. Impact harshness is up, obviously, but shoulder wear is down during hard cornering.  There are a number of 270 degree, constant radius entrance ramps to I-90 in my area, I would estimate the radius to be about 300 feet. They are posted at 35 MPH, and going 45 MPH through them at stock tire pressures means moderate understeer and scuffing on the front tires a little more than an inch up the sidewall. 40 psi. doesn’t change the understeer, but does preserve the sidewalls. I carry about .75 pounds of stuff in the glove box and front storage cubby, a couple CD’s , a flashlight, papers, and about 24 pounds of trunk stuff, tire pump, 2 gallons of windshield washer, jumper cables, etc. Yes yes, but this is my daily driver, and experience has shown that nothing tempts Murphy’s Law more to give you a flat than to run without a spare or jack. Leaving the spare out of my 1979 CHevy Impala did help, but the three flats I had in three years made the proposition less attractive.Â
 Originally, my cheif concern had been the elctric power steering, I was a little concerned that the weighting would feel artificial. If the car is stopped, very slight movements of the wheel will first take up the slack, admittedly, this steering system has very little slack, and then you feel the tourque from the electric boost motor kick in. While moving though, the effect is transparent. The wheel weighting is a little on the heavy side, the steering on my SE-R was lighter, 2nd gen RX-7’s are quite a bit lighter, but the motion feels fluid and low-friction. The steering ratio is fast, almost Z51 Corvette fast. The car feels stable at speed, even high speeds, [long, flat, open sections of Northern Michigan at say, 95, felt quite stable] and you can still get lots of wheel angle with little turning., my hands rarely leave 3 and 9 [thumbs on the spokes] in normal maneuvers. The throttle is light and needs some finess, I kept noticing at first that the revs would zing up almost a grand during every upshift. Apparently, my right foot was trying to take up gas pedal slack that wasn’t there, or I wasn’t letting off the gas as much as the car would like. My technique doesn’t feel any different now, but I have stopped doing that. The flywheel doesn’t feel specifically heavy, but it does hang onto revs, though in truth no more than other moderns cars. One big surprise was the lack of engine braking. I’ve never driven a 2-stroke Saab, so I can’t say that it freewheels quite that much, but I’m used to small cars with high compression engines and short gearing, which usually works out to a big fat jolt of engine braking. The Fit gently coasts down to idle, almost like it had an automatic. According to the Helm manual, the ECU shuts off the fuel injectors on overrun as a fuel saving strategy, so that may be the culprit. The brakes are strong, the EBD seems to make up for stomping on the brakes, it is very difficult to get the ABS to engage if all four wheels are on dry pavement. Get any one of them airborne, and it a different story.  I haven’t managed to corner hard enough to tricycle and trail brake at the same time, but given what the car does over bigger pavement lumps while braking suggests to me that it will go into “ice mode” in those conditions, which will make the braking very poor in those circumstances. Bear that in mind.
 Since the car is front drive, 64% of the weight up front, and no rear sway bar, it car will understeer, that’s just a fact of life. On constant-radius turns, the understeer is mild, but present. Decreasing-radius turns can be tricky, you have to be very concious of weight transfe,. It is all too easy to pile too much weight onto the outside front tire, which leads to massive understeer and yoyu just plow right off your intended line in a perfect tangent. I dove for a left turn lane with too much steering angle and too much decelleration and totally missed the lane I was aiming at. It was like I was driving in snow.Â
 Lift throttle oversteer does not seem to be a problem, you can take that any way you want to. A previous Hyundai Accent I had was quite sensitive to it, which made the car highly maneuverable, but uncomfortably twitchy, almost to the point of driving it like a rear-engined Porsche; brake only in a straight line, and accelerate through corners. In that car, you could quite clearly feel the dynamic center of gravity move back anf forth throughout the length of the car, depending on what you were doing. THe Fit is far less sensitive to it, which is great, most of the time, but a little tail-happiness wouldn’t be the worst thing in the world, from time to time. The Progress Group supposedly had a rear sway bar available now, I’ll have to check that out.Â
OK dammit, it’s been long enough, the Fit is here, the Fit is fully broken in, and I’ve done enough laps around Ohio now to have some sense of what it is actually trying to accomplish while I’m driving it.Â
 First, some particulars on me. I don’t race, I stopped street racing years ago, and most of the time i am usually trying to eke out maximum MPG to really piss off those fools who shell out thousands more on hybrids and can’t match the mileage numbers I get with my otherwise ordinary car. [I get between 39-43 MPG in mixed city/highway, by the way. EPA est. for the Fit is 31/38 city/highway.] But at the same time I do enjoy finding the apex, and driving in a spirited fashion. G forces are fun.Â
 Now, we can’t go for a drive unless the car is prepped properly. Mechanically, the car is still completely stock, right down to the 175/65-14 all season Dunlops. They are quiet, and ride pretty well, but I keep looking at Tire Rack ads for acceptable plus zero sizes. Stock pressures are 32 psi front and rear, but mex. press. on the tires themselves is a healthy 44 psi, so for the moment anyway, I’ve set the pressure at 40 psi front and rear. Impact harshness is up, obviously, but shoulder wear is down during hard cornering.  There are a number of 270 degree, constant radius entrance ramps to I-90 in my area, I would estimate the radius to be about 300 feet. They are posted at 35 MPH, and going 45 MPH through them at stock tire pressures means moderate understeer and scuffing on the front tires a little more than an inch up the sidewall. 40 psi. doesn’t change the understeer, but does preserve the sidewalls. I carry about .75 pounds of stuff in the glove box and front storage cubby, a couple CD’s , a flashlight, papers, and about 24 pounds of trunk stuff, tire pump, 2 gallons of windshield washer, jumper cables, etc. Yes yes, but this is my daily driver, and experience has shown that nothing tempts Murphy’s Law more to give you a flat than to run without a spare or jack. Leaving the spare out of my 1979 CHevy Impala did help, but the three flats I had in three years made the proposition less attractive.Â
 Originally, my cheif concern had been the elctric power steering, I was a little concerned that the weighting would feel artificial. If the car is stopped, very slight movements of the wheel will first take up the slack, admittedly, this steering system has very little slack, and then you feel the tourque from the electric boost motor kick in. While moving though, the effect is transparent. The wheel weighting is a little on the heavy side, the steering on my SE-R was lighter, 2nd gen RX-7’s are quite a bit lighter, but the motion feels fluid and low-friction. The steering ratio is fast, almost Z51 Corvette fast. The car feels stable at speed, even high speeds, [long, flat, open sections of Northern Michigan at say, 95, felt quite stable] and you can still get lots of wheel angle with little turning., my hands rarely leave 3 and 9 [thumbs on the spokes] in normal maneuvers. The throttle is light and needs some finess, I kept noticing at first that the revs would zing up almost a grand during every upshift. Apparently, my right foot was trying to take up gas pedal slack that wasn’t there, or I wasn’t letting off the gas as much as the car would like. My technique doesn’t feel any different now, but I have stopped doing that. The flywheel doesn’t feel specifically heavy, but it does hang onto revs, though in truth no more than other moderns cars. One big surprise was the lack of engine braking. I’ve never driven a 2-stroke Saab, so I can’t say that it freewheels quite that much, but I’m used to small cars with high compression engines and short gearing, which usually works out to a big fat jolt of engine braking. The Fit gently coasts down to idle, almost like it had an automatic. According to the Helm manual, the ECU shuts off the fuel injectors on overrun as a fuel saving strategy, so that may be the culprit. The brakes are strong, the EBD seems to make up for stomping on the brakes, it is very difficult to get the ABS to engage if all four wheels are on dry pavement. Get any one of them airborne, and it a different story.  I haven’t managed to corner hard enough to tricycle and trail brake at the same time, but given what the car does over bigger pavement lumps while braking suggests to me that it will go into “ice mode” in those conditions, which will make the braking very poor in those circumstances. Bear that in mind.
 Since the car is front drive, 64% of the weight up front, and no rear sway bar, it car will understeer, that’s just a fact of life. On constant-radius turns, the understeer is mild, but present. Decreasing-radius turns can be tricky, you have to be very concious of weight transfe,. It is all too easy to pile too much weight onto the outside front tire, which leads to massive understeer and yoyu just plow right off your intended line in a perfect tangent. I dove for a left turn lane with too much steering angle and too much decelleration and totally missed the lane I was aiming at. It was like I was driving in snow.Â
 Lift throttle oversteer does not seem to be a problem, you can take that any way you want to. A previous Hyundai Accent I had was quite sensitive to it, which made the car highly maneuverable, but uncomfortably twitchy, almost to the point of driving it like a rear-engined Porsche; brake only in a straight line, and accelerate through corners. In that car, you could quite clearly feel the dynamic center of gravity move back anf forth throughout the length of the car, depending on what you were doing. THe Fit is far less sensitive to it, which is great, most of the time, but a little tail-happiness wouldn’t be the worst thing in the world, from time to time. The Progress Group supposedly had a rear sway bar available now, I’ll have to check that out.Â
