The Dodge SRT-4 was a turbocharged sport compact introduced by DaimlerChrysler's Street and Racing Technology (SRT) in-house tuner group (originally known as PVO for Performance Vehicle Operations) in 2003. SRT stands for "Street and Racing Technology", and the "4" in the SRT-4's name denotes the number of cylinders it has. ACR and Commemorative Edition models were later introduced as well. The SRT-4 was designed for the racing and muscle car crowd, as well to attract younger buyers who had previously only considered owning Japanese sport compact cars.
Dodge, through its aftermarket parts distributor Mopar, also offers many performance enhancements for the SRT-4, from suspension bits to turbocharger-upgrade kits.
During its three years of production, the SRT-4 was considered by many to be the dominant vehicle in its class, regularly producing performance numbers equal or better than sports cars costing 2-to-3 times as much. The car was also a huge sales and marketing success for Dodge, with sales of over 25,000 units in less than 3 years of production. DaimlerChrysler expected to produce no more than 10,000 SRT-4s. 
Built in Belvidere, Illinois with 84% US content, the SRT-4 differed from the Neon, the model on which it was based, in many ways. From the outside, the SRT-4's unique front fascia was immediately noticeable. It also featured a large rear wing, unique rear fascia, side skirts, unique hood featuring a functional hood scoop, and special 17x6 inch wheels (16x7 on ACR model). Beyond aesthetics, the SRT-4's entire powertrain, suspension, braking system, exhaust, as well as much of the interior differed from the Neon.
Under the hood was a turbocharged 2.4 L I4 engine. This engine first appeared in the United States one year earlier in the 2002 Chrysler PT Cruiser GT, but had been used in the Mexican-market Dodge Stratus and Chrysler Cirrus LXi sedan for a few years before this. The SRT-4 used a New Venture Gear T-850 5-speed manual transmission (based on the unit from the European turbodiesel minivans), equal-length half shafts, and a high-capacity Sachs performance clutch. The suspension used stiffer springs, special Tokico struts, larger sway bars front and rear, firmer bushings, an upgraded steering rack from the PT Cruiser GT, upgraded knuckles, and a unique K-member. 11.0 inch (279 mm) vented disc brakes (with extra-thick rotors to prevent warping) were used in front, with 10.6 in (270 mm) non-vented discs in the rear.
Inside, the front seats featured enhanced lumbar and lateral support for performance driving, and a faux carbon fiber steering wheel and satin silver "cue ball" shift knob were used. The gauges had special SRT faces and silver rings matching those on the climate controls. An Auto-Meter brand boost gauge was used as well.
The 2004 model was updated with more power and torque, a torque-sensing Quaife limited-slip differential, larger fuel injectors, BF Goodrich KDW2 three-season ultra-high performance tires, and paint and trim changes. 2005 also featured new colors, but the important news was the return of the American Club Racing (ACR) edition. This package included wider BBS RX lightweight racing wheels with wider tires, 5-way adjustable Tokico Illumina shock absorbers, a stiffened suspension featuring a thicker rear sway bar, seats with pass-through slots for racing harnesses, officially allowed camber adjustment, and ACR logos on the exterior and embroidered on the front seats. A limited edition and numbered 2005 SRT-4 Commemorative Edition appearance package (in white with blue "Viper stripes") was also offered, but not with the ACR package.
- Power: 215 whp (2003 model), 230 whp (2004-2005 models).
- Torque: 245 ft·lbf @ 3000 rpm (2003 model), 250 ft·lbf @ 2200 rpm (2004-2005 models)
- 0-60 time: 5.3 seconds (Car & Driver)
- 1/4 mile time: 13.8-14.2 seconds (various magazine reviews)
- 1/4 mile speed: 98-103 mph (various magazine reviews)
- Top speed: 153 mph
Although most SRT-4s were rated at 230 hp, it was revealed that Dodge underrated the car's power production. Dodge tested the SRT-4 prototypes on the dyno with a fairly hot intercooler, which negatively affected overall efficiency. Most production SRT-4s in fact rate right around 230 hp at the wheels, with crank horsepower estimated at 265-275 hp. This makes them fairly formidable versus much more expensive production sports cars in real world, "roll-on" situations.
In real world use, SRT-4's have run high 13s to low 14s at 100 to 105 mph in the quarter mile with a capable driver. The fastest documented stock quarter mile time for a 2003 SRT-4 is 13.75 seconds @ 101.68 mph, with a trap-speed of 103.16 mph , while the fastest quarter mile times with documentation for more powerful 2004 to 2005 models include several 13.6s @ 105 mph. Those stock times included the use of the original, factory-equipped tires.
In 2004, Dodge engineers built a special SRT-4 for Sport Compact Car magazine using only factory upgrade Mopar performance parts in conjunction with lightweight, carbon fiber body peices for weight reduction. On drag slicks, it ran an 11.83-second pass at 123 mph in 70-degree weather.
The SRT-4 used an upgraded block (A855) from the similar block used in the turbocharged PT Cruiser. Both used the same cylinder head, however the intake manifold, turbocharger plumbing and intercooler are different. The SRT4 intercooler was a front-mounted cast aluminum 8-row unit produced by Valeo. The turbocharger was a reverse rotation Mitsubishi TD04LR-16Gk with a 6 cm² turbine inlet. Tight packaging forced some creative thinking on the turbocharger. The TD04 compressor has a compressor bypass valve built right into the compressor housing. The exhaust manifold and turbine housing were cast in one piece by Mitsubishi from high-nickel Ni-Resist steel. The one-piece design improved flow, reduced size and reduced thermal mass for quicker cat light-off. The turbine discharge was also part of the manifold/turbine housing casting, and it looped back around and hit the manifold again on its way to the catalytic converter. Where they met, there was a wastegate valve; keeping the wastegate valve away from the turbine housing improved flow where it mattered most. Maximum boost in stock form was around 14 lbf/in² (97 kPa).
Exhaust fumes exited through a catalytic converter, two resonators and a stainless steel mandrel bent 2.25 inch exhaust piping system, which split into two at the rear with no mufflers, for a distinct sound.
Paired with the SRT-4's turbocharged engine are a New Venture Gear T-850 high-performance 5-speed manual transmission, equal-length half shafts and a Sachs high-capacity performance clutch and pressure plate.
Suspension was rounded up with 170 lb (front) and 125 lb (rear) springs, specially valved Tokico struts, 24 mm front and 17 mm rear sway bars, firmer bushings, quicker ratio steering rack from the PT Cruiser GT, upgraded knuckles and a unique K-member.
Blending power and control was made possible by the interaction between the Dodge SRT-4 development team and performance operation engineers who cut their teeth in Sports Car Club of America (SCCA) racing. Braking consists of an ABS system with 11.0 in (279 mm) F vented/ 10.6 in (270 mm) R discs and single piston calipers (57 mm front/36 mm rear).
17 inch (45 mm offset) cast aluminum wheels coupled with 205/50/17 Michelin Pilot Sport tires helped put the power to the ground on 2003 models, with 2004 and 2005 models getting BF Goodrich KDW2 tires. Even wider 225/45/16 BF Goodrich KDW2 tires on lightweight BBS racing wheels (40 mm offset) were offered on the ACR model in 2005. The standard 17 inch wheels were purposely designed to look like aftermarket wheels, and the unique spoke pattern allowed for better airflow to the brakes. The design showed much similarity to the TSW VX1 wheels found on the 2001 concept supercharged Neon S-R/T.
External key features
Of note aesthetically, when Dodge was redesigning the SRT-4 pre-production model in late 2002 prior to its release, they added two vents on the front fascia to help with the upgraded cooling system, a revised boost gauge face, and standard pedals instead of the aluminum ones that would be used on later SRT-4s.
The taller, basket-handle type spoiler also improved vehicle handling by generating downforce and providing a stabilizing effect at high speeds.
Inside the cabin, taking cues from the seats in the Dodge Viper SRT-10, the SRT-4 front seats had enhanced lumbar and lateral sections for better support during racing-type maneuvers. The agate-colored cloth on the body of the seats was textured for better grip through the corners. The side bolsters of the front seats were trimmed in vinyl and curved to stabilize occupants, further enhancing the performance racing feel of the vehicle. The car's rear seats also featured the textured fabric.
Carbon-fiber-look leather wrapped the top of the SRT-4's steering wheel for greater control. A satin silver cue ball shift knob topped a shifter that was surrounded by a boot made of the same textured carbon-fiber-look leather as the steering wheel. The steering wheel's unique three-spoke design also provided a better view of the instrument cluster gauges.
Unique gauge designs in the SRT-4 (which were exclusive to the SRT lineup) featured special silver faces with satin silver ring accents. The same satin metal trim was also featured on the instrument panel center stack, climate control knobs and on the door handles. A silver Auto-Meter brand turbo boost/vacuum gauge was to the right of the instrument cluster.
Along those lines, the SRT-4's boost/vacuum gauge was located to the right of the instrument cluster. Unlike aftermarket gauges, the SRT-4 turbo gauge was incorporated as a design element of the dashboard.
The SRT-4's roots came from SCCA racing. Dodge intended a package of performance, styling and quality at a low cost, and has shown what the SRT-4 is capable of in motorsports, campaigning the SRT-4 in Rally, SCCA and drag racing circuits, with much success.
2005 Commemorative Edition
Available for 2005 was the SRT-4 Commemorative Edition. This model (along with the Viper SRT-10 and Ram SRT-10) was created to celebrate the SRT vehicles. The limited, numbered edition SRT-4 included "Electric Blue" stripes over the white-colored body, blue stitching on the floor mats, shifter boot, seats and steering wheel, stainless steel door sill plates and a numbered plaque. No performance extras were added on the Commemorative Edition.
- 2004 John Lingenfelter Memorial Trophy
- Won a Top Ten Car award in Sport Compact Car (SCC) in 2003, 2004, and 2005 - all three years the SRT-4 was produced.
Named the 2003 Car of the Year by SCC. 
Won numerous comparsions in several U.S. automotive magazines from 2003 to 2005, including:
- 1st place - SuperFour Super Car Challenge, Car and Driver magazine, November 2005. The SRT-4 competed against 14 other performance vehicles.
- 1st place - Serial Thrillers Comparo, Car and Driver magazine, May 2004.
- 1st place - Compact Sports Cars test, Automobile magazine, March 2004.
- 1st place - Edmunds comparison test, August 2003
- 1st place - Tough Crowd comparison test, SCC, January 2003. The SRT-4's performance dwarfed that of every competitor in nearly every category of the test.
In 2004, the SRT-4 got a chance to prove its status as a racer when Dodge's director of racing operations, John Fernandez, headed up an assault on the SCCA's T2 (Touring car II) racing class. The class had been dominated by the Camaro Z28 for several years, but in just its first year on the racing circuit the SRT-4 proved to be a match for the LS1-powered Camaros, taking home several wins with just two factory-sponsored SRT-4's competing.
Multiple SRT-4s are currently raced in the SCCA SPEED World Challenge - Touring Car Series, and in just their second year have already become one of the more successful platforms in the series. 
- 2003 SRT-4 Road Test by Sport Compact Car magazine, January 2003
- 2004 SRT-4 Road Test by Car and Driver magazine, April 2004
- MNMopar.org - The Internet's Original Mopar Enthusiast's Group