This website tracks and shares information about a demonstration project taking place at the University of Michigan in the Department of Mechanical Engineering.
In this demonstration project, a 2013 Chevy Cruze turbodiesel vehicle and a 2014 GM Sierra turbodiesel vehicle will be operating for more than 12 months on 100% renewable diesel fuel. The vehicle performance and fuel economy will be tracked during the demonstration to explore the impacts of operation on 100% renewable diesel fuel.
Vehicles – this is a photo of the Chevy Cruze at the UM North Campus with its “wrap” to help with public outreach.
Fuels – the vehicles in this demonstration project have been running on 100% renewable diesel fuel from Neste Oil, who make this fuel via the hydrodeoxygenation of vegetable oils and animal fats. Their website explains the feedstocks and processes they use to make this fuel.
Vehicle refueling occurs at the W.E. Lay Auto Lab, on the UM North Campus. This is a photo of the Cruze being refueled at the Auto Lab.
Test Program – the test vehicles operated on retail diesel fuel (D2) from March 19, 2020 until December 2, 2020. They began operation on Neste Oil 100% renewable diesel fuel (RD) on December 2, 2020. We are tracking fuel economy and vehicle performance on 100% RD to assess potential long term impacts. During the winter months of operation on RD, no low temperature issues arose with the RD fuel.
Below are specifications of these fuels and some interim fuel economy results obtain as of May 2021. Because RD has less energy per gallon, we are expecting to see a loss of fuel economy when operating on RD relative to D2, simply because of the difference in energy content per volume of fuel.
Fuel Properties
| Property / Fuel Type | Diesel (D2, retail/pump fuel, summer) | Renewable Diesel Fuel (RD) |
| Density (kg/m3) | 835 | ~780 |
| Lower Heating Value (MJ/kg) | 43.1 | 44.1 |
| Lower Heating Value (MJ/liter) | 36 | 34.4 |
| Carbon Intensity (gCO2e/MJ) | 95 | 16.9 – 39 * |
| Cetane Number | 47 | 75.5 |
* depends on the feedstock, with lower CI being associated with recycled cooking oils
Fuel Economy Measurements – Chevy Cruze Turbodiesel Test Vehicle
The table below shows the typical urban (Ann Arbor city driving, commuting, ~ 5 miles each way) fuel economy and highway fuel economy from a test drive from Ann Arbor to Cleveland, OH (roughly 150 miles). Operation on D2 and RD included both warm and cold weather operation. The fuel economy data below are
| Fuel / Driving Condition | City (Ann Arbor, MI) | Highway (Ann Arbor, MI to Cleveland, OH) |
| Diesel fuel (mpg), D2, retail / pump fuel | 24.5 | 46.2 |
| Renewable Diesel Fuel (mpg), RD |
25.3 | 49.8 |
To date, rather than a 5% reduction in real-world MPG that we would expect because RD has less energy per gallon, the Chevy Cruze operating on RD gets increased fuel economy in the city and on the highway. This could be the result of a number of factors including:
- Higher cetane number – improved ignition quality due to the higher Derived Cetane Number (DCN) of the RD, leading to improved combustion phasing and better thermal efficiency and thereby, fuel conversion efficiency
- Lower sooting tendency – RD does not contain aromatic compounds that tend to increase the sooting tendency of the fuel. A lower sooting tendency would lead to a slower rate of soot accumulation in the diesel particulate filter (DPF), reducing the pumping losses of the engine, because soot accumulation in the DPF causes exhaust backpressure to increase. Thus, operating on RD may reduce the amount of time the vehicle spends with elevated DPF backpressure.
Moreover, using the fuel economy, and carbon intensities listed above, the Chevy Cruze Turbodiesel operating on Renewable Diesel Fuel is achieving somewhere between 61% and 84% carbon intensity reduction when compared to operating on conventional, petroleum-derived diesel fuel.