Position 1: 346 km/h
Position 2: 343 km/h
Position 3: 339 km/h
Position 4: 334 km/h
Position 5: 329 km/h
So the fix is to set the BodyDragHeightAvg and BodyDragHeightDiff values under the [BODYAERO] heading to "0.00" as the AI cars aren't affected at all by these two values while the player car very much is.
-----------------------------
Lancia Fulvia HF 1.2
1967 Targa Florio
Car class: GT1.3
Car numbers: 8, 10
Engine: Lancia V4/12° DOHC
Displacement: 1200 cc
Power: 97 hp at 6200 rpm
Top speed: 168 km/h
Gearbox: 4-speed
Weight: 830 kg
Fuel tank: 38 l
-----------------------------
Lancia Fulvia HF 1.3
1967 Targa Florio
Car class: GT1.3
Car numbers: 2, 4, 12, 14, 16
Engine: Lancia V4/12° DOHC
Displacement: 1300 cc
Power: 108 hp at 6000 rpm
Top speed: 174 km/h
Gearbox: 4-speed
Weight: 845 kg
Fuel tank: 38 l
-----------------------------
Lancia Fulvia HF Speciale
1967 Sebring 12h
Car class: P2.0
Car number: 56
1967 Targa Florio
Car class: P2.0
Car number: 178
Engine: Lancia V4/12° DOHC
Displacement: 1300 cc
Power: 120 hp at 6500 rpm
Top speed: 183 km/h
Gearbox: 4-speed
Weight: 825 kg
Fuel tank: 38 l
-----------------------------