Significant Accounting Policies

Principles of Consolidation

The consolidated financial statements include the financial statements of the Company and its wholly owned subsidiaries. All intercompany transactions, including intercompany profits and losses and intercompany balances, have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the U.S requires management of the Company to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosure of contingent liabilities. These estimates and assumptions are based on management's best estimates and judgment. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to impairment of goodwill and long-lived assets, stock-based compensation, the fair value of financial instruments including warrants, allowance for doubtful accounts, inventory valuation, taxes and contingent and accrued liabilities. The Company bases its estimates on historical experience and various other factors, including the current economic environment, which it believes to be reasonable under the circumstances. Estimates and assumptions are adjusted when facts and circumstances dictate. Actual results may differ from these estimates under different assumptions and conditions. Management believes that the estimates are reasonable.

Cash

Cash consists of cash balances on hand and on deposit at banks. Cash on deposit at banks at times may exceed the Federal Deposit Insurance Corporation (FDIC) limits. The Company believes no significant concentration of credit risk exists with respect to these cash balances.

Accounts Receivable

Accounts receivable are recorded at the invoiced amount and do not bear interest. Accounts receivable are presented net of a reserve for doubtful accounts of $0.5 million and $0.4 million at December 31, 2017 and 2016, respectively. The allowance for doubtful accounts is the Company's best estimate of the amount of probable credit losses in the Company's existing accounts receivable. The Company determines the allowance based on historical write-off experience and past due balances over 90 days that are reviewed individually for collectability. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. The Company does not have any off balance sheet credit exposure related to its customers.

Inventories

Inventories are stated at the lower of cost (FIFO method) or market (net realizable value). Finished goods inventory includes materials, labor and manufacturing overhead. The Company establishes provisions for inventory that is obsolete or when quantities on hand are in excess of estimated forecasted demand. The creation of such provisions results in a write-down of inventory to net realizable value and a charge to cost of sales.

The Company's inventory includes precious metals (platinum, palladium and rhodium) for use in the manufacturing of catalysts. The precious metals are valued at the lower of cost or net realizable value, consistent with the Company's other inventory.

Property and Equipment

Property and equipment is capitalized at cost and is stated at cost less accumulated depreciation and amortization. Depreciation and amortization is determined using the straight line method over the estimated useful lives of the various asset classes. Machinery and equipment are depreciated over 2 to 10 years; furniture and fixtures, computer hardware and software and vehicles are depreciated over 2 to 5 years. Property and equipment held under capital leases and leasehold improvements are amortized over the shorter of estimated useful lives or the lease term. Repairs and maintenance are charged to expense as incurred and major replacements or betterments are capitalized.

Intangible Assets

The Company's intangible assets consist of trade names, acquired patents and technology, and customer relationships and have finite lives. Intangible assets are carried at cost, less accumulated amortization. Amortization is computed on a straight-line or accelerated basis over the estimated useful lives of the respective assets, ranging from 4 to 20 years.

Long Lived Assets

Assets such as property and equipment and amortizable intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. An impairment loss is recognized when the sum of the expected undiscounted future net cash flows of an asset or asset group is less than its carrying amount and is measured as the amount by which the carrying amount of the asset or asset group exceeds its fair value.

Warrants and Derivative Liabilities

The Company accounts for the issuance of Company derivative equity instruments in accordance with Accounting Standards Codification ("ASC") 815-40 "Derivative and Hedging". The Company reviews common stock purchase warrants at each balance sheet date based upon the characteristics and provision of each particular instrument and classifies them on the balance sheet as equity or a liability. Below are some of the factors the Company considers with the corresponding balance sheet classification:


•	Equity if the awards (i) require physical settlement or net-share settlement, or (ii) give the Company a choice of net-cash settlement or settlement in the Company's own shares (physical settlement or net-share settlement), or as


•	Liabilities if the awards (i) require net-cash settlement (including a requirement to net-cash settle the contract if an event occurs and if that event is outside the Company's control), or (ii) give the counterparty a choice of net-cash settlement or settlement in shares (physical settlement of net-share settlement).

The Company assesses classification of common stock purchase warrants and other freestanding derivatives at each reporting date to determine whether a change in classification between assets and liabilities and equity is required.

Income Taxes

Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance against deferred tax assets is required if, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. The valuation allowance should be sufficient to reduce the deferred tax assets to the amount that is more likely than not to be realized.

The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Changes in recognition or measurement are reflected in the period in which the change occurs. The Company records interest and penalties related to unrecognized tax benefit in income tax expense.

Revenue Recognition

Revenues are derived primarily from the sale of products. The Company generally recognizes revenue when products are shipped and the customer takes ownership and assumes risk of loss, collection of the relevant receivable is reasonably assured, persuasive evidence of an arrangement exists and the sales price is fixed or determinable. There are certain customers where risk of loss transfers at destination point and revenue is recognized when product is delivered to the destination. For these customers, revenue is recognized upon receipt at the customer's warehouse. When terms of sale include subjective customer acceptance criteria, the Company defers revenue until the acceptance criteria are met. The determination of whether or not the customer acceptance terms are perfunctory or inconsequential impacts the amount and timing of the revenue recognized.

Research and Development

Research and development costs are generally expensed as incurred. These expenses include compensation expense for employees and contractors engaged in research, design and development activities, as well costs paid to outside parties for testing, validation and certification of our products. Also included is any depreciation related to assets utilized in the development of new products.

Stock-Based Compensation

Equity awards consist of stock options and restricted stock units ("RSUs"). The Company measures the compensation cost for all stock-based awards at fair value on the date of grant and recognizes it on a straight-line basis over the service period for awards expected to vest, which is generally three years.

The Company measures the fair value of stock options using the Black-Scholes option-pricing model and certain assumptions, including the expected life of the stock options, an expected forfeiture rate and the expected volatility of its common stock. The fair value of RSUs is based on the closing price of the Company's common stock on the grant date.

Product Warranty

The Company provides for the estimated cost of product warranties in cost of sales, at the time product revenue is recognized. Warranty costs are estimated primarily using historical warranty information in conjunction with current engineering assessments applied to the Company's expected repair or replacement costs.

Foreign Currency

The functional currency of our subsidiary Engine Control Systems Europe AB in Sweden is the Swedish krona and the Clean Diesel Technologies Limited U.K. subsidiary, is the British pound sterling. Accordingly, the assets and liabilities of the foreign locations are translated into U.S. dollars at period-end exchange rates. Revenue and expense accounts are translated at the average exchange rates for the period. The resulting foreign currency exchange adjustments are charged or credited directly to other comprehensive income or loss as a separate component of stockholders' equity. Unrealized foreign currency exchange gains and losses on certain intercompany transactions that are of a long-term investment nature (i.e. settlement is not planned or anticipated in the foreseeable future) are also recorded in other comprehensive income or loss in stockholders' equity. Accumulated other comprehensive loss contained only foreign currency translation adjustments as of December 31, 2017 and 2016.

The Company has exposure to multiple currencies. The primary exposure is between the U.S. dollar, the Canadian dollar, the Euro, British pound sterling and Swedish krona. Gains and losses arising from transactions denominated in currencies other than the functional currency of the entity are included in other income (expense) in the consolidated statements of comprehensive loss. Gains and losses arising from transactions denominated in foreign currencies are primarily related to inter-company loans that have been determined to be temporary in nature, cash, accounts receivable and accounts payable denominated in non-functional currencies.

Net Loss per Share

Basic net loss per share is computed using the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed using the weighted average number of common shares and dilutive potential common shares. Dilutive potential common shares include employee stock options, RSUs, warrants and debt that are convertible into the Company's common stock.

Diluted net loss per share excludes certain dilutive potential common shares outstanding as their effect is anti-dilutive. Because the Company incurred net losses in the years ended December 31, 2017 and 2016, the effect of potentially dilutive securities has been excluded in the computation of net loss per share as their impact would be anti-dilutive. Potentially dilutive common stock equivalents excluded were 1.9 million and 2.1 million shares during the years ended December 31, 2017 and 2016, respectively.

Fair Value Measurements

Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset and liability. As a basis for considering such assumptions, a fair value hierarchy has been established that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (level 1 measurement) and the lowest priority to unobservable inputs (level 3 measurements). The three levels of the fair value hierarchy are as follows:


•	Level 1: Quoted prices (unadjusted) in active markets for identical assets or liabilities;


•	Level 2: Inputs other than quoted prices included within Level 1 that are either directly or indirectly observable including quoted prices for similar instruments in active markets and quoted prices for identical or similar instruments in markets that are not active; and


•	Level 3: Unobservable inputs in which little or no market activity exists, therefore requiring an entity to develop its own assumptions about the assumptions that market participants would use in pricing.

Fair Value of Financial Instruments

ASC Topic 825, "Financial Instruments", requires disclosure of the fair value of financial instruments for which the determination of fair value is practicable. The fair values of the Company's cash, trade accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses and other current liabilities approximate carrying values due to the short maturity of these instruments. The fair value of borrowings under the line of credit approximates their carrying value due to the variable interest rates. The fair value of shareholder notes payable, calculated using level 3 inputs, and a net present value model, was $1.8 million at December 31, 2016. The fair value for the warrants classified as liability and the bifurcated derivative liabilities were calculated using level 3 inputs, including Black-Scholes option-pricing model as well as Monte Carlo Simulation model. These inputs are disclosed in Note 14 "Fair Value Measurements"

Recently Issued Accounting Guidance

In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-9, "Revenue from Contracts with Customers (Topic 606)". ASU No. 2014-9 supersedes the revenue recognition requirements in "Revenue Recognition (Topic 605)". ASU No. 2014-9 requires entities to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. In July 2015, the FASB finalized the delay of the effective date by one year, making the new standard effective for interim periods and annual periods beginning after December 15, 2017. Early adoption is permitted, but it is not permitted earlier than the original effective date. ASU No. 2014-9 provides for either full retrospective adoption or a modified retrospective adoption by which it is applied only to the most current period presented. While the Company has not finalized the impact of the adoption of ASU No. 2014-9 on its consolidated financial statements, the Company does not expect the adoption to have a material impact.

In January 2016, FASB issued ASU No. 2016-1, "Recognition and Measurement of Financial Assets and Financial Liabilities". ASU No. 2016-1 requires equity investments to be measured at fair value with changes in fair value recognized in net income; simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment; eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; requires separate presentation of financial assets and financial liabilities by measurement category and form of financial assets on the balance sheet or the accompanying notes to the financial statements and clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets. ASU No. 2016-1 is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. While the Company has not finalized the impact of the adoption of ASU No. 2016-1 on its consolidated financial statements, the Company does not expect the adoption to have a material impact.

In February 2016, the FASB issued ASU No. 2016-2, "Leases (Topic 842)." ASU No. 2016-2 requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous U.S. generally accepted accounting principles. It is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. Entities are required to recognize and measure leases at the beginning of the earliest period presented using a modified retrospective approach. While the Company has not finalized the impact of adoption of ASU No. 2016-2 on its consolidated financial statements, the Company does not expect the adoption to have a material impact.

In August 2016, the FASB issued ASU No. 2016-15, “Classification of Certain Cash Receipts and Cash Payments: a consensus of the Emerging Task Force.” ASU No. 2016-15 provides guidance on how certain cash receipts and payments are presented and classified in the statement of cash flows, including debt prepayment or debt extinguishment costs, contingent consideration payments made after a business combination, and separately identifiable cash flows and application of the predominance principle. The standard is intended to reduce current diversity in practice. The standard will be effective for annual reporting periods beginning after December 15, 2017, including interim periods within those reporting periods. Early adoption is permitted. While the Company has not finalized the impact of adoption of ASU No. 2016-15 on its consolidated financial statements, the Company does not expect the adoption to have a material impact.

In October 2016, the FASB issued ASU No. 2016-16, “Intra-Entity Transfers of Assets of Other Than Inventory.” Current GAAP prohibits the recognition of current and deferred income taxes for an intra-entity asset transfer until the asset has been sold to an outside party. ASU No. 2016-16 updates the current guidance by requiring that entities recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The amendments in this ASU do not change GAAP for the pre-tax effects of an intra-entity asset transfer under Topic 810, Consolidation, or for the income tax effects of an intra-entity transfer of inventory. The standard will be effective for annual reporting periods beginning after December 15, 2017, including interim periods within those reporting periods. Early adoption is permitted. While the Company has not finalized the impact of adoption of ASU No. 2016-16 on its consolidated financial statements, the Company does not expect the adoption to have a material impact.