A sleeper Volvo wagon once owned by actor and racing driver Paul Newman is being auctioned off by RM Sotheby's.

This 1998 Volvo V90 is nicknamed "Volvette" because it's powered by a Chevrolet LS2 6.0-liter V-8—the kind used in the C6 Corvette. Newman had commissioned two previous engine-swapped Volvo wagons, but this third and final build was a surprise from his racing team, who included a plaque on the dashboard. The wagon was given to Newman in 2007, but the actor died in 2008, so he didn't get much chance to enjoy it.

Ex-Paul Newman 1998 Volvo V90 wagon (photo via RM Sotheby's)

Ex-Paul Newman 1998 Volvo V90 wagon (photo via RM Sotheby's)

The small block V-8 is coupled to a General Motors-sourced 4-speed automatic transmission. The wagon's rear-wheel-drive layout made it an ideal candidate for a V-8 engine swap, but the stock driveshaft still had to be shortened. The stock inline-6 and transmission are included with the sale.

Other modifications include an altered shift linkage to line up with the Volvo center console, reworked wiring, and a modified front suspension. The latter may have included some Porsche 911 components, according to RM Sotheby's, while the rear suspension remained stock. In keeping with Newman's taste, the exterior was left stock except for a custom rear badge reading "V06."

Ex-Paul Newman 1998 Volvo V90 wagon (photo via RM Sotheby's)

Ex-Paul Newman 1998 Volvo V90 wagon (photo via RM Sotheby's)

One of Newman's other modified Volvo wagons was a 960 with a supercharged 5.0-liter V-8 from a Ford Mustang. Newman convinced friend and fellow celebrity car enthusiast David Letterman to buy one as well, and it was featured on "Comedians in Cars Getting Coffee" with Jerry Seinfeld.

Prior to that, Newman had the turbocharged 3.8-liter V-6 from a Buick Grand National stuffed into the engine bay of a 1988 Volvo 740 Turbo wagon. Also sporting a 5-speed manual transmission from a Pontiac Firebird, this car sold for $80,740 on Bring a Trailer earlier this year.

The auction for the "Volvette" ends on June 13. RM Sotheby's had an initial estimate of $20,000-$25,000, but the current bidding sits at $40,000 with plenty of time to go.