Electric SUV revealed ahead of LA debut, will arrive in American driveways from late-2020.

The Rivian R1S has been unveiled ahead of its in-the-flesh debut tomorrow at the 2018 Los Angeles motor show.

Measuring 5040mm long, 2015mm wide, 1820mm tall, and riding on 3075mm wheelbase, the R1S is about the same size as the Chevrolet Tahoe, the Suburban's short wheelbase sibling, and significantly shorter from head to toe than the R1T ute, which it shares its skateboard chassis with.

Like the R1T, the R1S will be offered with three battery pack options. The base 105kWh model has a claimed range of over 385km, the 135kWh version is good for around 500km, and the top-shelf 180kWh model capable of about 660km.

Model for model, the SUV has about 15 kilometres more range than the equivalent ute. All models have an electric motor for each wheel, and a top speed of 201km/h.

Performance is unchanged, with the 300kW/560Nm base model capable of a 0-60mph time of 4.9s, and the higher capacity variants topping out at 562kW/1120Nm and a claimed 0-60mph time of 3.0s.

Compared to the R1T, the R1S has a significantly lower towing capacity of 3500kg, down from 5000kg.

The low- and mid-spec R1S has seating for seven over three rows, while the top-tier variant maxes out at five people.

The R1S will also be available with camera, LIDAR, radar, high-precision GPS, and high-definition maps for Level 3 self-driving capability.

Other features include over-the-air software updates, eight airbags, a 15.6-inch infotainment touchscreen, 12.3-inch instrumentation screen, and a 6.8-inch touchscreen for the second row.

Rivian says the R1S can ford water up to a metre deep. In off-road mode, the R1S has an approach angle of 34 degrees, a departure angle of 30 degrees, and a breakover angle of 29 degrees.

Both Rivian models will be produced at Mitsubishi's old factory in Normal, Illinois. Deliveries are scheduled to commence in late 2020. Orders can be placed now via a refundable US$1000 ($1380) deposit.

The entry-level 105kWh model is priced from US$72,500 ($99,800) before the US$7500 ($10,300) federal tax credit. Only the more expensive 135kWh and 180kWh models will be produced initially.