16V 2.3 COSWORTH
The Cosworth engine was based on the M102 four cylinder 2.3-litre 8-valve unit producing 136 hp (101 kW; 138 PS), already fitted to the 190 and E-Class. Cosworth developed the cylinder head. It was made from light alloy using Coscast's unique casting process and brought with it dual overhead camshafts and four valves per cylinder, meaning 16 valves total which were developed to be the "largest that could practically be fitted into the combustion chamber".
In roadgoing trim, the 2.3 L 16-valve engine generated a maximum power output of 185 hp (138 kW) at 6,200 rpm and 174 lb⋅ft (236 N⋅m) at 4,500 rpm. The oversquare 95.50 x 80.25 mm bore and stroke dimensions ensured that the car could easily rev up to the 7,000 rpm redline. Acceleration from 0–100 km/h (62 mph) was in less than eight seconds, and the top speed was 230 km/h (143 mph).
US-Specification cars had a slightly reduced compression ratio (9.7:1 instead of 10.5:1), and were rated at 167 hp (125 kW; 169 PS) at 5,800 rpm and 162 lb⋅ft (220 N⋅m) at 4,750 rpm.
The road-going version of the engine was reconfigured with reduced inlet and exhaust port sizes, different camshaft profiles, no dry sump configuration and Bosch K-jetronic replacing the specialised Kugelfischer fuel injection. These changes helped bring power down to the required 185 bhp (138 kW) specification, but still resulted in a "remarkably flexible engine, with a very flat torque curve and a wide power band". The heads for the engines were cast at Cosworth's Coscast foundry in Worcester and sent to Germany to be fitted to the rest of the engine, parts of which were different from the standard 2.3-litre engine including light pressed alloy pistons, and rings designed to withstand higher engine speeds, whilst con-rods, bearings and bearing caps were found to be strong enough as standard and left unaltered.
Due to their performance, the 16-valve cars were different from the other 190 models. The body kit on the 2.3-16 and 2.5-16 reduced the drag coefficient to 0.32, one of the lowest CD values on a four-door saloon of the time, whilst also reducing lift at speed. The steering ratio was quicker and the steering wheel smaller than that on other 190s, whilst the fuel tank was enlarged from 55 to 70 L. The Getrag 5-speed manual gearbox was unique to the 16-valve and featured a dog-leg change pattern, shifting down and left for first. The gearchange quality was, however, noted as "notchy, baulky", criticisms which weren't levelled at the BMW M3 (E30) which shared the same gearbox. An oil cooler was fitted to ensure sufficient oil cooling for the inevitable track use many of these cars were destined for.
The strictly four-seater interior had Recaro sports seats with strong side bolsters for front and rear passengers. Three extra dials - an oil temperature gauge, stopwatch and voltmeter - were included in the centre console. The 190 E 2.3-16 was available in only two colours, Blue-Black metallic (Pearl Black in the US), and Smoke Silver. The 2.5-16 added Almandine Red and Astral Silver.
All 2.3-16-valve 190 models are fitted with a Limited Slip Differential (LSD) as standard. They were also available with Mercedes' ASD system which was standard equipment on the 2.5-16v. The ASD is an electronically controlled, hydraulically locking differential which activates automatically when required. The electronic control allows varied amounts of differential lock from the standard 15% right up to 100%. It is not a traction control system however, and can only maximize traction rather than prevent wheel spin. Activation of the ASD system is indicated by an illuminating amber triangle in the speedometer.
The suspension on 16-valve models is modified from the standard 190 (W201). As well as being lower and stiffer, it has quicker dampers, larger anti-roll bars, harder bushings and hydraulic Self-levelling suspension (SLS) on the rear. This allows the rear ride height to remain constant even when the car is fully loaded.