Build a car
Set the numbers and watch what falls out of them. Everything here runs through the same physics the catalogue's cars are modelled with: not a simplified version for hypotheticals but the identical functions, so a car you invent and a car someone built are measured by one ruler.
Nothing is stored. The build is written into this page's address as you type, so sending someone the link sends them the car.
Start from
Starting positions for a car you are inventing, not figures about a car anyone built. Nothing here is sourced and nothing here is meant to be. Pick the nearest one and change all of it.
Engine and mass
The acceleration model integrates power, not torque: at any instant the force at the wheels is limited by power over speed, or by grip, whichever is lower. Torque is carried on the build and shown for comparison, but changing it alone will not change the modelled figures.
Body, aerodynamics and grip
Frontal area estimated at 2.23 m² from width × height. Estimated as 0.85 × width × height = 0.85 × 1.800 m × 1.460 m ≈ 2.23 m². Not a measured figure.
Gearing
Road speed at 1000 rpm in top gear, and the engine speed the run ends at. One number each, both readable off a tachometer, which is why the model asks for these rather than for a ratio, a final drive and a tyre size. Leave them blank and the top speed is purely where power meets drag, which is what every car in the catalogue gets.
Geared for
252km/h
2,857 rpm at 120 km/h.
Measure the shape
The dimensions above are a body, and the wind tunnel will run it and report what it measures. Send that back into the build and every figure below recomputes from a Cd nobody typed: a lower roof, a tighter wake, a higher top speed, each step computed rather than asserted. Set the dimensions first: the shape is built when the solver starts, and changing them afterwards means building it again.
A lattice-Boltzmann solver, running on your GPU. It starts only when you ask it to.
The build’s Cd
0.29
What the performance model is using right now. Yours to set, and yours to replace with the measurement on the right.
This solver, on a fitted shape
—
Measured on a representative shape fitted to the dimensions you set. Nobody has published a Cd for a shape you just invented, so there is nothing to validate it against and none is claimed. It is what this solver, at this resolution, measured.
What you are looking at, stated plainly. A real lattice-Boltzmann solver running on your GPU. The smoke is carried by the velocity field it computes, not a decorative particle effect, and turning the car re-rasterises the body the fluid sees. But the body is a representative shape stretched onto the dimensions you set, not a scan of a car. At — mm per cell it resolves large-scale separation and the shape of the wake; it does not resolve the near-wall boundary layer, the gap between tyre and arch, or absolute drag to engineering tolerance. Treat the number above as a property of the shape at this scale, not of a car.
My C-segment, modelled
This build is written into the page's address as you type. Nothing is saved anywhere, so the link is the only copy, and it is enough.
0–100 km/h
modelled
No published figure to compare against.
Top speed
modelled
No published figure to compare against.
Braking 100–0
modelled
Tyre-limited ideal. Ignores fade and assumes peak grip throughout. A floor, not a test result.
Power to weight
at kerb weight
Traction-limited to 34 km/h: grip, not power, sets the launch.
Acceleration
Speed against time, integrated forward: traction-limited off the line, then power-limited.
Power required against speed
Where the curve meets the flat line is the top speed. Drag rises with the cube of speed, which is why the last 20 km/h cost more than the first 100.
Dashed line: 99 kW at the wheels, after drivetrain losses. Horizontal axis in km/h.
Holding a steady speed
- Power at the wheels
- 20.0 kW
- Spent on drag
- 74%
- Steady-state use
- 7.4 L/100 km
A constant speed on level ground, not a drive cycle. Not comparable with a WLTP or EPA figure.
Below about 72 km/h rolling resistance dominates; above it, drag does.
Aerodynamic drag
Cd 0.29 × 2.23 m² = CdA 0.648 m². Frontal area estimated.
Newtons against km/h.
Estimated as 0.85 × width × height = 0.85 × 1.800 m × 1.460 m ≈ 2.23 m². Not a measured figure.
Every figure on this page is modelled, not measured. The formulae and every default constant are published on the methodology page, including where the model is weakest: it knows nothing about gearing, so a car that runs out of gears before it runs out of power will model faster than it really is.