Gas-Electric Hybrid Rally Car

Gas-Electric Hybrid Rally Car

My latest design is a four-wheel drive, parallel hybrid sports coupe. The design joins a Honda CRX with the independent rear suspension, brakes and differential off an old Subaru. Instead of powering the rear axles through a transfer case and driveshaft, they are powered by an electric traction motor. The objective is to create a sporty four-wheel drive vehicle that exceeds the performance and fuel economy of any automobile ever produced. The most efficient 4WD passenger vehicle I found in my research is the 88 Subaru Justy. Its 66 horsepower 1.2L 3 cylinder engine can move this 1800 pound car 35 miles with a gallon of gas. Its performance is far from sporty, crawling up to 60 MPH in 12 seconds. The base 1986 Honda CRX si is a great platform to work from since it weighs less than 2000 lbs and goes 0-60 in 8.5 seconds. The only 4WD's that met that acceleration get approx 20 mpg city/24 HWY.

The stock 86 CRX si is spec'ed at 30/33 MPG yet I typically get over 35 MPG (not bad for a sports coupe.) The additional static and rotating mass of the rear drive axles will inherently slow the acceleration and reduce efficiency in stop and go traffic. The electric rear traction motor should be selected to provide enough power to at least offset the weight penalty, but ideally should have surplus power to improve acceleration. The controller must be carefully programmed to provide electric assistance during the engines least efficient RPM ranges and during limited traction. The controller could tap directly into the stock fuel-injection ECU to acquire data about throttle postion, engine speed, and manifold pressure. Additional sensors for wheel speed are needed to determine when the wheels are slipping. Independent rear traction control could be added by applying brakes to the wheel spinning, thus transferring power across the open differential to the other wheel. This is inspired by both low tech, home built sand rails and modern Land Rovers.