Originally Posted by Lower

I have one of these, very low end models. It is useful for comparing before and after mods, but I certainly wouldn't go around quoting times from it as proof. It seems pretty accurate on 1/4 mile time (within 1/10th I'd guess), but the MPH is way off -I'd guess it to be 6-7% high.

It measures:
1* 0 to 60 mph time
1* 1/4 mile elapsed time (E.T.)
2* 1/4 mile trap speed
4* Instantaneous lateral acceleration (G s)
4* Sustained lateral acceleration (G s)
3* 60 mph braking distance
3* Instantaneous braking Gs
3* Sustained braking Gs
5* Horsepower

1= Useful, and accurate enough to give a person a good idea of what real times might be. The only thing this low end does well enough to even worry about.

2= Far enough off that you'll wonder how it can be as accurate on the 2 items (see #1) that it is actually accurate on. 6-7 % high, I'd guess.

3= I don't autocross, nor do I care about braking distance unless it's a distance of "not soon enough", but by then it's too late. I'd assume that the 60-0 would be accurate, based upon the 0-60 being acceptable.

4= I still don't autocross. Lateral G's? Who cares? Not me. Want to measure them? Mount the unit sideways -seems pretty cheesy. Might be accurate, but I somehow doubt it.

5= Horsepower. HAHAHAHHAAHHA!
Ahem. What an utterly useless addition. I have no idea how they tested this and found it to be within 5%, let alone 50%. yes it is that far off. And you could test it 10 times down the same stretch, and never get 2 numbers within 25 HP, I'd bet. This measurement is just junk.

Lastly, before I bought one of these again, I'd drive around and try to find a flat, straight road. I mean flat and straight. I live in SE MN, and there is one (seemingly) flat 1/2 mile stretch within 30 miles of my house. 1. And even it may not be flat enough.
Seriously.
It needs to be perfectly flat... and straight.
No.
Even flatter than that road you are thinking of.
Nope, flatter than that road too.

Honestly. Spend the hours upon hours that I have driving around looking for a flat road. You never realise how unflat a road is until you actually need a perfect one. And it can't be curvy either. Flat and straight.