Best 8 Tuneable Sleeper Cars
BMW 335d saloon
Standard power & torque 282bhp & 428 lb/ft
Potential power & torque Over 350bhp & 550 lb/ft
The car that changed people’s perceptions of diesel performance, the 335d is a monstrous car straight out the factory thanks to almost 430 lb/ft. But when a simple remap can push it to 350bhp and over 530 lb/ft, giving it M3-beating performance, you can see why it had to feature here.
The reputation of the turbocharged 335 BMWs in both petrol and diesel form is already pretty high, so a 335d coupe with the optional M Sport bodywork is not a sleeper. You need a plain saloon version, maybe even with 320d badges.
Unfortunately as yet there isn’t much off-the shelf tuning available for the 335d, beyond an exhaust system and a remap. But we suspect things like uprated intercoolers and induction setups will be coming soon and give equally huge gains. If diesel tuning takes off as much as it has in the USA, then 335ds sporting massive turbos and serious grunt may soon be seen. Maybe you can be the first?
PROS: Seriously rapid fast with just a remap; has the chassis and suspension to cope with big power increases too.
CONS: Beyond the remap not much is available, yet! Coupe or M-styled versions are too nice looking to be considered as true sleepers.