The lightest production Lamborghini model :

Lamborghini Miura P400 S.

Lamborghini type :	Overall weight :
Miura Jota	900 Kg
P400 Miura Roadster :	1000 Kg
P400 Miura S :	1040 Kg
350 GT :	1050 Kg
LP400 Countach :	1065 Kg
P250 Urraco :	1100 Kg
P200 Urraco :	1100 Kg
LP400 S Countach :	1200 Kg
Islero :	1240 Kg
Silhouette :	1240 Kg
P400 Miura SV :	1245 Kg
400 GT :	1249 Kg
400 GT 2+2 :	1249 Kg
P400 Miura :	1292 Kg
P300 Urraco :	1300 Kg
Gallardo :	1430 Kg
Gallardo SE :	1430 Kg
Diablo SE30 JOTA:	1450 Kg
Diablo SE30 :	1451 Kg
Diablo GT :	1460 Kg
Islero S :	1460 Kg
400 GTS Jarama :	1460 Kg
Espada Series I :	1480 Kg
LP500 S Countach :	1490 Kg
LP500 Countach QuattroValvole :	1490 Kg
Countach 25th Anniversary :	1490 Kg
Jalpa P350 :	1510 Kg
Diablo SV (1999) :	1530 Kg
400 GT Jarama :	1540 Kg
Gallardo Spyder :	1570 Kg
Diablo (1990-1998) :	1576 Kg
Diablo SV (1995-1998):	1576 Kg
Diablo VT (1993-1998) :	1625 Kg
Diablo VT Roadster (1995-1998) :	1625 Kg
Diablo VT (1999) :	1625 Kg
Diablo VT Roadster (1999) :	1625 Kg
Diablo VT 6.0 :	1625 Kg
Diablo Millennium Roadster :	1625 Kg
Espada Series II :	1635 Kg
Espada Series III :	1635 Kg
Murciélago Roadster :	1650 Kg
Murciélago 6.2 :	1650 Kg
Murciélago LP640 :	1665 Kg
LM 002 :	2700 Kg

When looking at the overall weight of supercars lately, you'll notice they get heavier each year, the Zonda C12 is about the only supercar at 1250 Kg, while the smaller De Tomaso Guara reaches 1200 Kg, it's in another league than the Zonda. Other 'supercars' in these regions are the Viper GTS (1293 Kg), the Porsche GT3 (1350 Kg) which actually beats the faster Porsche Turbo. The big Diablo competitor, the Ferrari 550 Maranello does actually reach a healthy 1716 Kg, about 90 Kg heavier than the Diablo 6.0 VT.